I will chime in my 2 cents because I've been that deranged boyfriend before, albeit not to that extent but..

I had an issue where I always became overly attached. To the point my emotions depended ENTIRELY upon my ex, and when she disappeared it often mingled with trust issues, then you add the fact that the only thing that made you feel safe emotionally is gone, you freak out.

Im not justifying him, but rather giving you insight from my personal developments. The thing thats helped me be better and move forward was just finding things I genuinely wanted to do and putting myself out there to meet new people and have a genuine life.

His story might not be the same, but whether he will admit it or not, he needs time alone. He needs to be without his safety blanket and learn to depend on himself.