Hugs to you.
I felt this way even a few weeks ago, but have since had a bit of an epiphany (or a 2x4, if I have to be honest)...
All I say, I say gently and with compassion for your suffering...
I'm wondering: what does your WH want you to change and try harder with? What does he think is just "never good enough?"
I notice you wrote a similar post to this one almost a year ago (Aug 2013) - what have you and your WH been doing to heal since that time? You felt like this a year ago - are you still with him because you don't have a choice (which is the only reason I myself stayed for so long), or because you deeply care about him and want to end up with him after all that's happened?
He's still with you - do you think it's because he needs you, or because he wants you? What does he do to make you feel loved? What do YOU do to make HIM feel loved?
What has he done to gain back your trust?
You said in your bio:"You see in my family we just got by and survived it. There was no encouragement or support to find a passion, set goals or become successful at anything (that would require too much or attention) . Therefore I've just been fumbling through this marriage for the past 17 years. I've been lost and still am. I have no idea who I am, what I like or what my dreams are."
...You just outlined a HUGE problem from your past that is plaguing your present (and, btw, I could have written that exact same thing about my upbringing). And because you haven't learned any other way of coping, you continue still to perpetuate those poor coping skills.
So, do you know who you are, what you like, or what your dreams are YET?
Have you been waiting for your WH to fix everything that is wrong in your lives? There is definitely a LOT that he needs to work on, but the one thing he surely can't fix is YOU.
Can you face the thought of fixing YOU yet? Can you focus on yourself and work on making peace with the broken past you dragged into your present? I'm not discounting your pain on any level - trust me! I know what you're going through!
I bet so much of your apathy and pain would be alleviated by you staring unflinchingly into your past, reaching out a caring, gentle, supportive hand to that little girl who never felt cared about, and treating her the way she needed and DESERVED to be treated.
You won't get that from ANYONE else but yourself.. It's just not possible. Your family can't do it or they would have years ago. And do yourself a favor and stop looking for it from your WH - he isn't capable, and even if he was, it really wouldn't help you on your personal journey to find your inner strength and love anyway (though his support and understanding while you attend to your life-long wounds would certainly help).
When is the last time you were KIND to yourself? Not kind to yourself because you're feeling sorry for yourself, but KIND to yourself because you deserve kindness? When is the last time you felt love for yourself? Have you ever? I never learned how to love myself, so I've been searching my whole life for someone else to love me in my stead. But it has only backfired. I am learning that I can't ask anyone to do something for me that I am not willing to do for myself. It reeks of dysfunction.
If you haven't defined yourself yet, maybe it's time to? Maybe your brain and soul are tired of being aimless. Like me, maybe you're desperate for something worthwhile to focus on? It seems like apathy is your comfort zone (as is mine), and this affair business has taken over because it's a safe place to harbor your resentments. But clearly apathy has done nothing for you your whole life.
You certainly know what makes you sad... but what makes you happy? What brings you joy - and do you share that joy with your family?
When is the last time your kids saw a genuine smile on your face? When is the last time they saw you share a happy or flirty or supportive or even just contented moment with your WH? (I ask because I know my own poor child is STARVED for that type of affectionate display between her parents after 2.5 years of watching them mope and fight and slam doors and roll their eyes at each other and be generally cold and dismissive.)
When is the last time you focused on YOU - NOT ON HOW YOU FEEL ABOUT THE AFFAIR - but on YOU? Your needs, your desires, your fears and dreams and hopes and joys... when is the last time (if EVER) you connected with YOU deep down? Who are you and what do you want?
I hope I haven't given you the impression that I let your WH off the hook on any level for what he did to your marriage, your trust, and your spirit. He has some serious issues to work out. But he's still THERE - he's still WITH YOU. That means something, I believe.
Take this opportunity and BUILD YOURSELF. Forget about him for now. This is YOUR TIME to find out who you are and what your passion is. And don't forget: your passion in life is NOT your WH's affair! It's just where you parked your apathy and insecurity for the time being because no one took the time to teach you to love yourself and treat yourself with kindness and pride. Be proud of what you've done in your life! And then go find your passion and do MORE things to be proud of!
And practice this mantra: It's not about him. It's not about him. It's not about him.
This is your time. Show your kids how to love themselves by your own example. Show them what courage and strength and commitment and dedication to overcoming adversity looks like.
(PLEASE! Forgive my presumption if I've overstepped my bounds as a fellow sufferer. What I just wrote is what I myself needed to hear, so if this is too forward/assuming/direct - feel free to disregard it all. I hope some of it helps you or even another reader, but if not, peace to you and good luck on your journey.)