The Sexual Healing Journey by Wendy Maltz. Opened my eyes by showing me that sexual deviancy is not an uncommon reaction to childhood sexual abuse (CSA). Also if she is reluctant to start IC or it's not an option, have her go to rainn.org. They have a free, confidential counseling service by phone or live chat. I did one session on live chat and it was just amazing that the counselor "got me" immediately. And zero judgment about my cheating. That chat session, and the book, helped me overcome my resistance to IC. Which has helped me immensely.
Feel free to have her PM me.