I am so sorry for your pain. Facebook and social media have destroyed many marriages and in my view is a horrible creation. When fb came along, my ex made a point to reconnect with everyone that she has ever known, and spent more time on fb with them than focusing on our marriage. I can honestly say that her addiction to fb helped destroy our marriage. She too was defensive about cutting off relationships on fb like yours. It takes great courage for you to go to marriage counseling and give her another chance. I am in therapy currently, which I started last summer. I wish I had started therapy years ago. I hope you find a good therapist on your own to go to in addition to marriage counseling. If you are a book reader, I have been reading a book which has been helpful, "love like you've never been hurt" by jentezen franklin. Even though he is a pastor writing the book, it is not religion shoved down your throat, but a book of real pain and how to deal with it. Maybe you can find comfort in the book too.