Sexual addiction and infidelity are two different things, and it sounds as if they are being confused here. Going to SA meetings is PART OF the work a WS (who is an SA) should be doing, but the outcomes of SA meetings really have little to do with your marriage and the trauma of infidelity. To me, that's almost like having a broken stove and wondering why taking cooking classes isn't fixing it. Knowing how to cook and care for your stove will help in the future to prevent further breakage of the stove, but you need a repairman to fix what's broken now. Or a new stove.
WH attends meetings every day sometimes 2-3 times a day.
Can I ask about this? Why is he practically living at the SA meetings? New AA members (for example) are often encouraged to do "30 meetings in 30 days" in order to get started, which in itself is a little extreme, but it's just to get things started, then you switch to a less intensive meeting schedule, often weekly or less. I would assume SA is the same. Someone please correct me if I'm wrong (I'm not an SA). To me, I'd be a little curious if he's meeting someone there, or not actually going and just saying he is. It sounds fishy to me.
ChamomileTea and Hellfire are 100% correct in my opinion, and that is my experience in my own recovery as a WS and in our marriage. Short of a time machine, what was done cannot be undone, and there is nothing in heaven and earth that will make what happened "go away" or "feel settled". It's like losing a limb. There are things you can do to help mitigate the loss, but the loss and the damage done are permanent. It's a big loss and a big adjustment, yes, and everyone needs time and space to accept it. But at the end of the day, you either choose to focus on your pain and loss, or you choose to be a survivor, and focus on who you want to be, and what kind of life you want to live moving forward. You own your happiness and joy, and he owns his. Whether you can move forward in your new lives together is the real question.
Your healing is your own, and your husband's healing is his own. The idea isn't to "heal as a couple". Rather, you both need to deal with your own trauma and recover as individuals. Then, when both of you are healthy enough to even consider a new relationship (with each other or with someone new) you restart the process, from the beginning, almost as if you had never met. Because you haven't, at least, not as healthy individuals.
Following Gottman, after an A nothing can happen before atonement/amends
From my own experience, I find this... worded poorly. I don't see how one can atone for a betrayal. "I'm sorry" doesn't help. What helps the most, in my mind, is to have the other person be capable of true empathy and personal accountability. It isn't so much about what they say or do, it is more about who they are at their core. Jeffery Dahmer and Mother Teresa and two completely different people for example. Who they are, their motivations, how they identify themselves, what kind of energy they put out into the world... that's what makes us who we are. For example, if you accidentally hit and killed a child with your car, how would you feel? My guess is, you'd be devastated, unable to sleep or eat, unable to stop thinking about the loss that occurred and the emotional pain and suffering of the parents, etc. It's not just guilt, it's more about understanding the devastation you caused, and then doing anything and everything in your life to make sure that never, ever, happens again, even if that might mean not driving anymore.
WS's are often incapable of this level of self-realization, at least, in their current state of mind. They are too selfish, too inwardly focused, and often focus on trying to "do or say the right thing" in order to make this go away so that they can finally feel better about themselves. That approach does not work, ever. The way you feel better about yourself is by being a better person, and often, that means a LOT of therapy and hard work, an understanding of how you got to the point where you betrayed someone else in the first place, and most importantly, why it wasn't important enough for them to respect themselves enough (let alone their spouse and kids) to not do so in the first place.
My only advice is to try and step away from the thought process that there is something he can do or say that will make you feel better, or trust him more. He can't. You will trust him more when he does the hard work to become a more trustworthy person at his core. When that happens, if that happens, you will know it, because it will be as obvious as the sun in the sky.