Also, if you are into reading books, I would recommend 2 for you:
1) Not Just Friends - will help you to understand what is going on between you, your W, and OM
2) No More Mr. Nice Guy - sounds like you are similar to me in that you take care of people, focus on your W, etc. to the detriment of yourself. If so, this is a quick read that explains why this is not good (it's not really being nice, it's a way of being indirectly manipulative) and how to get past it.
Me 42, W 39, S8, S6, S2 M 11y, A & ILYBNILWY 11/08 Walking away from a bad situation.