1) her husband has been backstabbing me and supporting my W.
(I know... wrong is wrong regardless of what the person is like or doing... but I could see him somehow twisting me contacting him to his advantage with his W... putting me down for stooping to that level, which he would never do)

I think the best thing you could do for both of them is tell him. That would be an act of decency, grace and class despite the fact that he has backstabbed you. I think you should rise above it and do him a good turn.

While he might be mad at first, it will give him a heads up and he will come to appreciate it some day. Besides, if there is nothing wrong with adultery, as her family avers, then there should be no issue.

"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena.." Theodore Roosevelt

Exposure 101