my advice.......RUN don't walk, don't skip, don't look back, don't second guess.....just RUN!
I know of what I speak. my ex dil went ahead and married my son. She knew beforehand. Everything was and still is a disaster. We are continuing to sift through the wreckage.
There is no "up side" is a situation as yours.
Take care of yourself and get far, far, away. If not physically them emotionally.
dixied (sorry to be blunt but I have lived the nightmare in a front row seat.)