My sister and I not to long ago went through a dramatic realization about the religion we were raised in, and so largely on the principle of skepticism towards spiritual answers, we stand agnostic.
During her experience, she went though a lot of depression because of the way our family reacted. Because of her depression, and how busy her husband was, my other brother in law took advantage of being with my sister, to help give her council, by having an affair with her. Both of them were guilty of the process, but I can't help but feel more sympathy towards my sister than my brother in law, especially after he has been holding his wife (my other sister) back from counselling.
Now, much later down the road, many of the burnt bridges have been rebuilt (minus the ties between the two couples that the affair occurred between). My sister has gone through a comparable binge/purge cycle, of forgiving herself, and hating herself. Her husband forgave her, and they both have been to counselling, and they deal with it pretty well, but sometimes my sister just gets really down on herself about it.
She can't help but feel like she is just no good for her husband, and that one day he might just leave her because he has every right to leave. If anything, I would see him leaving her because she gets too caught up in this thinking and bringing it back up. I don't know what to say to her, to help her get over it, i'm thinking that she wishes she could just have a clean start, but there isn't really a way to do that without a divorce, which I know she also doesn't want to leave her husband. It has been a fair amount of time since it all happened, that I don't think she is going to get over this until something big impacts her.