I'm just going to point out what I've read before- from Sandi-
Your W's R w OM caved...who knows what happened, maybe he rejected her...she could be using the sex as a way to control you and make her feel better.
I would follow rrs advice and only consider it...I think its a bad idea to follow through.
I've had sex twice w/ W back in Novemeber--UGGGHHH...I do regret it b/c OM was in the picture, and b/c it showed that I was readily available to W...I don't regret it b/c it may have been the last time I was intimate w/ W...before that was Sept.
Just be wary...other posters had diff experiences, I think Robx was having sex w/ his W pretty regularly then nixed it b/c he wanted something more...a female WAW poster said that her having sex w/ her LBH actually helped their sitch...
Again, every sitch is different...for now, only consider...