It looks like it's too late in this relationship, but in my opinion the problem with the guy needs to be addressed first (assuming his mother's description is accurate). Then we'll see how much of a problem there is left with the woman. I suspect she's intrenched now. This is a gross simplification of course, there are not enough details.
I'm not looking at it through victims or not victims, but just how the dynamics of this thing works. I would hate for my mother to have described me as sweet, true or not