BeYourself-
Less about the use of a substance and more directly about affairs was a book called After the Affair by Janis Abrahms Spring.
I am not trying to make a statement about if you had an affair or not, but I learned a lot from the book because it talked about typical feelings that each person had once the truth came out. It helped me make a lot more sense of things.
I agree that my hubby's relationship and mine was not in a good place when he did what he did.
My learning curve for myself though, was why did I stick it out, when it was not meeting my needs? Why did I not toss in the towel so much earlier when I knew it was not working? Why did I have to allow myself to have so much hurt.
Regardless of who did what and the technical definitions of it all, that is a repeated piece I keep coming around to in my learning.