I can relate to a couple of the things you mentioned in your post, and I'd like to invite you to copy your post into a new thread under the "Sex-Starved Marriage" forum.
Self care is so important. You will feel so much better when you start doing more for yourself. I am a big advocate of exercise. For me, it helps clear my mind and keep my attitude positive. I hope you consider regular exercise as part of your plan.
You are particularly blessed that your husband wants to work on improving your relationship. If both of you are committed to working on the marriage, you will surely see progress. It is never an easy road, but it is well worth it.
Spend some time reading posts under the Newcomers and Infidelity sections. You will learn so much about possible perspectives/stances of your husband. You will also be convinced to never ever cheat, and certainly not destroy your marriage and family without the hardest fight of your life. That would be the most foolish thing you could do to yourself and to those you love.
Have you read any of Michele Weiner-Davis' books yet? I recommend "The Sex-Starved Marriage" as a start.
