While I think there's a place for therapeutic escorts, I question if it's a good idea for someone who has such a personal relationship with her to do that. Coming out of a monogamous abusive relationship doesn't seem like the best time to start sleeping with a best friend's husband - It's bound to get everyone looking at the past, present, and future with a microscope.
If she can work through her issues and be totally open and honest, I say go for it. It sounds like before she can do this, she'll have to work on her relationship with you.
“Edit yourself, bitch. Edit yourself.” – Chad Michaels