I have not read the SSM book, so I don't know if it would help you or not. When I was young and dating, I used to listen to that Crosby, Still and Nash song, Love the One You're With. (I know you think I am crazy with all these song lyrics, but I think songs make have a huge influence on the listeners.)

The song is rather a trite treatment of your problem, but then it isn't either. Because it is a matter of setting aside the idea that this is a big hurdle to cross and making it more like a line on the sidewalk -- something easy to step over. I really do believe that there is nothing to it but to do it. You need to investigate what is stopping you. You were able to have sex with OM while married to your husband. Why can't you have sex with your husband while still emotionally involved with OM? Please don't tell me you can't be unfaithful. I will throw up.

Love the One You’re With
by Stephen Stills

If you’re down and confused, and you don’t remember who you’re talkin’ to. Concentration slip away, ‘cause your baby is so far away.

Well there’s a rose in the fisted glove and the eagle flies with the dove, and if you can’t be with the one you love, honey, love the one you’re with, love the one you’re with, love the one you’re with, love the one you’re with.

Don’t be angry, don’t be sad, and don’t sit cryin’ over good times you’ve had. There’s a girl right next to you, and she’s just waitin’ for something to do.

And there’s a rose in the fisted glove and the eagle flies with the dove, and if you can’t be with the one you love, honey, love the one you’re with, love the one you’re with, love the one you’re with, love the one you’re with.

Turn your heartache right into joy, she’s a girl, and you’re a boy. Well get it together, make it real nice,
You ain’t gonna need anymore advice.

And there’s a rose in the fisted glove and the eagle flies with the dove, and if you can’t be with the one you love, honey, love the one you’re with, love the one you’re with, love the one you’re with, love the one you’re with.