Jeannie,
Your circumstances just break my heart. When you and your husband both posted on here, I felt like I was on the set of "An Officer and a Gentleman". It was so sweet! To read your posts now is just heartbreaking. Come to think of it, maybe you should find your husband's post and ask him what happened to that man. I do understand getting past the honeymoon phase though. Mine and my husband's lasted for over two years, and it was amazing, but life has pretty much become normal again which is not nearly as exciting, but nothing can stay "new" forever. You said:
I worry. I hate that my relationship with my husband is so closely correlated with my relationship with God. I hate that I have let both slide. I hate that the only time I seem to get close to God is in the wake of some marital tragedy. I hate that my husband's indescretions have wrecked the way I see myself. I hate that trust is so hard to get to. I get angry and depressed and I sort of shut down. I lose "me" I am hopeful that actually venting these feeling will give me a chance to work through them.
The counseling idea is a great one. After an infidelity it is normal to try to do everything in our power to make ourselves "worthy" of our spouse's love and undivided attention, but we have to put that focus on God. God is the one we have to prove ourselves worthy to. As long as He is satisfied with us, our husbands should be. If they aren't that is their problem not ours. Maybe you are finally coming to that realization. Maybe that is why you are starting to feel a peace that you can live without your husband if you have to. I know that happened to me, and it was such a relief. It was very freeing to know I was going to be ok either way things went. Even if my husband wasn't there, God would be, and He was all I needed. That's not to say I don't love my husband and that I don't try to please him, but he isn't and shouldn't be number one in my life. If we can really get our priorities in order and keep them in order, everything else starts to work out. It stands to reason after your husband's repeated failures that you would be scared. You wouldn't be human if you weren't, but just know that God will never leave you nor forsake you. He has been there for you when your husband has let you down. He is the only one you can always count on. You may feel far from Him at times, but He is always right there with you.
You may have to get tough with your husband, and the next time he questions your mental stability, agree with him and tell him you are questioning it too since you keep loving and trying to please a man that doesn't show any interest in spending time with you and the family.

It does seem you have become a doormat for him. Definitely don't plead and beg, but do stand up for yourself. Your marriage can't grow if the two of you don't spend time together. As has been stated, you do deserve better. You are in my prayers.