I'm so sorry you are going through this and I can feel your pain in your posts! I'm thinking about you and sending you strength to get through this rough time.
Whether or not he is having another Affair it really doesn't matter b/c an affair is a reaction to issues in the marriage. You can spend your energy trying to figure that our, or spend your energy trying to realize why your marriage is failing.
Is there anything that you think can save your marriage? Have you asked your H that? Sometimes, it takes hitting rock bottom to come to the realization as to what it means to have a crumbling marriage and to allow yourself to recognize what's gone wrong through the years.
I would agree with the MLC, if it wasn't for the issues you had years previously. It seems to me more like a broken relationship, than a MLC. I believe in repair for broken relationships...has he shown any glimpses of repair?
H & I, both 32, together since 18. *M 7/03, A since 9/06. Bomb 7/07, H ended it w/ OW 9/08 * Agreed to D 6/09...very hard *D 8/10 * At peace, have become great friends w/ X-H and his new GF