How was the majority of the marriage? When did it start getting worse? What would your W say the issues were? How long was it sexless, and who's decision was that? Why did W have an affair last time around? Why did she end it then? Did you two try to make any changes at that point?
Lot of questions, but I think that would help us all understand the dynamic a bit more.
Until then read everything you can, and don't make any major moves until the dust settles.
PS- I am reading my kids LOTR! I read it as a kid, but now it is totally different, and reading this with my S12 and D9 is making it my favorite book. We read the last chapter tomorrow, after over a year we are finally finishing it! I can't believe it! My S12 pointed out to me it took us as long to read as it took them to go on their journey and back. Anyway, love the screen name.
Me:38 XW:38 T:11 years M:8 years Kids: S14, D11, D7 BD/Move out day: 6/17/14, D final Dec 15