I'm sorry you're going through this
...
I dealt with my bitterness through the Basic Seminars at
www.embassyinstitute.org (first seminar is free--but they are ALL SO GOOD!)
Bill Gothard's teaching is powerful straight from the Word of God... I didn't even know I was free from bitterness until hubby told me some hurtful truths and I realized ' oh my, how come I don't hate him?' It was easier to forgive.
I'm going through my own sadness... at least your husband is willing to stay with you. Mine wants nothing to do with me at all... because he doesn't really want to change.