Ah, gotta love the shame/guilt cycle, our oldest, dearest friend, the one that likely got us in trouble in the first place...
I think, to some degree, that the shame can be good (and yes, I am very cautious in saying that) because it is a tool and a motivator for change. But in much the same way that morphine is a good tool for managing pain but you need to be cautious to not get addicted, shame can motivate you but you can also get lost in it.
They say that shame = "I'm a bad person", while guilt = "I did a bad thing, but it does not define me". I think that's a good starting place to understand shame, and to plan on how to get out of that never-ending loop.
Shame is what we were missing during the affair. We had no shame. Shame might have stopped us. If we have it now, that's a step in the right direction. It at least means you are seeing you did something wrong and feel badly about it. If you can't understand what you did wrong and why it was wrong then fixing it will be a lot harder.
In order to get past shame however, we need to realize that it buys us nothing. Here's the thing.
Shame = "I am a bad person, at my core. It is who I am. It is what I will always be. I will never be forgiven. I will never be worthy. I will die old and alone and unloved and I deserve nothing more".
Is that who you WANT to be? Is that the outcome you desire?
For many WS's, while it is not what they want, they lack self-love and self-value to the point where they actually believe they are intrinsically unworthy of love or forgiveness, or incapable of being anything more or different than they are and always have been. ALL of this is bullshit that we tell ourselves to fit the paradigm of who we are. For me, and I think for most others, it is all rooted in FEAR and PAIN. I don't care how wonderful or horrible your life is/was, no one in this world escapes without their unfair share of pain and fear. Don't ever compare pain. It doesn't work that way. Often you will hear the phrase, "Well, I had a shitty childhood too, but I didn't...<whatever you did>". Ignore them. Their life isn't your life, and they have issues you don't have. No one is an angel, no one is without sin, everyone has regrets. So don't be bullied into believing that you are somehow a bad person for being flawed. You are a human being. Unless you are a psychopath or serial killer, odds are you are just a very broken person who would like to be a better person. So be a better person.
Guilt = "I did a bad thing, and other people got hurt as a result. I am not always a bad person however. I did a bad thing because something within me allowed me to compromise my morals and values, to put my self before others, and allowed me to justify my actions when I knew they were wrong. There are times in my life when I do good things, moral things, decent, unselfish and caring things too. Because I am capable of decency and love, I know I am not fundamentally flawed. I just need to improve the parts of me I don't like."
This is really the key. You need to know that you still have value. That even though you did something horrible and hurt people who didn't deserve it, you do still have value, and are deserving of love, from yourself and others. You need to know that you can ALWAYS CHOOSE TO BE A BETTER PERSON, and while that will never undo the past, it will go a long way towards preventing future damage, and to some degree, it actually gives dignity back to the people you hurt.
Think about this. During the affair, you lied, you betrayed, you deceived and dismissed your spouse or partner. Most BS's will tell you that it is the worst thing you could have ever have done to them. But in my opinion, there is one thing left that you can do that will hurt your spouse even more, and will continue to hurt them forever... you can NOT give a shit. You can NOT try. You can just stay the same POS that hurt them and continue to be that POS for the rest of your life, the same sad little puppy who can't even make an effort, a real effort, to do what they can to clean up their mess and prevent it from happening again. It is just my opinion, but THAT is the worst thing you could do to them. So don't do that. Don't be that person.
Living in the shame spiral means that you are being that person. The one who twists the knife in their spouses back deeper and harder than ever before simply by remaining the person who hurt them. The one question every BS asks themself is "Did my spouse ever really love me in the first place?" When you give up and live in the shame spiral, your answer to them is a resounding, "No, I never really loved you, nor was I capable of loving anyone, and I will never change". If you'd like to give your spouse a reason to leave and yourself a reason to be dead inside, this is the path to take.
If however you want to give your marriage and your life every possible shot, stop living a life feeling as if you are the ultimate loser, have a reason and a purpose to get up in the morning, and actually see and experience happiness again in your life, then you need to get out of the shame spiral and get on to fixing those things in your life that you don't want.
The first thing every WS seems to ask (myself included) is "How do I do that? How do I fix my own shit?" And if someone has some concrete ideas on that, I'd love to hear them. Until there, here is what I'm doing, and it is helping to some degree (not perfect, but not nothing).
1) Identify what you don't like. For me, some really easy ones were the things I did during the affair. I don't like being a liar. I don't like being untrustworthy. At some point, you need to just make a decision about how you are going to handle things. Don't lie. Don't decieve. I started out by trying to be as honest as I could, in everything. If the check wasn't in the mail, I said so. If those jeans make your ass look fat, I tell you. If I ate the last cookie you asked me not to eat, I fess up and suffer the consequences. Just... be who you want to be. For some things, it is simply a matter of doing it.
2) Dig deep - ask your 5-year-old self who you are. Who did you want to be as a kid? Did you ever say, "I want to be a liar and a cheater when I grow up?" Probably not. I hope not. Did you want to be a hero? Did you want to be a parent? Did you want to be someone special? How about just an honest, decent and respectful person? BE the person your 5 year old self always wanted to be.
3) Model yourself after someone you respect, and hang around people that act like you want to be. If you hang around with druggies, you are more likely to be a druggie. If you hang around with guys that demean women, your likely to do so too. If you hang around people who love their spouses and sacrifice for their kids and families, you are more likely to be that person as well. If you read about and socialize with people who live lives that you admire and respect, then that will become your goal. No one is perfect, that's okay. It doesn't mean you can't aim high however.
4) Get to know yourself. Read a little Brene Brown and Pema Chodron. Join a yoga class or practice mindfulness. Volunteer at your church or kids school. Get a hobby, work on a career you want. Whatever you do, do so with open eyes. See yourself for who you really are. WS's have so much bullshit built up inside themselves that it takes a while to dig it all out and get past it to the truth, and that takes time and effort. Don't rush it, but don't give up on it either.
5) Work on empathy. Every single day, try to imagine how other people think and feel. Acknowledge their feelings, relate to them. If you don't know what's going on with them, ask. Empathy is hard especially when you've been selfish for so long. (I'm still working on it!) Simple phrases such as , "That must be frustrating for you", or "You must have been really glad when that happened", or "You seem distracted. What's going on?" can really put you in touch with others. Try every day to get out of your own head and into other people's lives.
6) Don't let fear and doubt stop you. Again, something I need to work on. But it's the truth. Right now your spouse doesn't believe a word you say or a thing you do, and that can be very hurtful and demoralizing. And yeah, we brought it on ourselves and deserve that. But that's not a reason to not try. If you love your spouse, tell them. Maybe it take saying that 1000 times before they start to believe you. Maybe a million. So you better get started. Don't let fear of trying stop you, and don't let failing stop you. See each mistake as a learning opportunity. Now you know what doesn't work. Now you were reminded of a place in your life that you need to work on. I know, it can be frustrating, and sometimes we look and think, "I'll never change fast enough to save my relationship", and that might be true. I'm sorry about that. Consequences suck, but they are what they are. It's not a reason to quit or not try.
7) Some words of wisdom my wife gave to me. "Who do you want to be? If you were to die tomorrow, what would you want people to think about you? Would you want them to say, "He had his demons, and they got the better of him"? Or would you rather they say, "He made some bad mistakes in life, but he sure worked hard to overcome them and be a better person"?
8) Put more effort into fixing your relationship than you did tearing it apart. Look, during your affair, you put effort into doing it. Each affair is slightly different, but odds are that you made time to write the AP, or see them. You met up somewhere, you covered it up, you made up lies, you held secrets, you argued with your spouse, and so on... it was all shitty effort, but it was effort. Put more effort into saving your marriage and yourself than you did in the affair. Put yourself and your spouse and your marriage first, and make them them a higher priority than you made your AP and the affair.
That's all I've got at the moment. Keep coming back to SI, keep asking for help. You are NOT alone and don't listen to those who come on here complaining that everyone is mean to them, and don't they deserve a hug? Yeah, everyone deserves a hug, but not from the people they just stabbed in the back, and not from the people that are here to give you some hard, honest truth and 2x4's. Can people be mean? Sometimes. But most of the time, what they are being is HONEST. When it hurts the most is when you need to listen the hardest, and do a little introspection. The truth stings, but it also will free you. Stop doing things that you are ashamed of, and you will stop being ashamed. Stop doing things that are dishonest and deceitful, and you will need to hide anything or be ashamed of your actions. Do your best in all things and you will never regret not having tried harder. It is really that simple, and yet that hard.