(((((SG)))))
I am so very very sorry that you are having to go through this.
Sending prayers for you, your family, and the family of the girl.
I do not believe that 'your sticking to your boundaries' did this to him. From what I have read it looks like she is a very talented young lady and she certainly is very very pretty. I can see why your son was drawn to her and to me shows that he was on the road to recovery. He was looking UP not down, and had his eyes on the brass ring. And from what I read, comments from those that know the girlfriend, that she is a pretty level headed young lady. Broke up with the exbf because he was 'too controlling.' That tells me that she thought pretty well of your son.
Again sending good thoughts and prayers to all of you, and asking her HP to guide her to some counseling for her own sanity.
We are here for you.
Love and hugs,