He is an adult, regardless of the foolishness of his choices and/or going crazy or whatever you think is up with him. As the book says, you're not going to be able to educate him regarding his problems. So let him be. He is not your project and he is responsible for himself and his own actions. If you're genuinely concerned for your safety, then get restraining orders and/or talk to attorney and/or police.
IF in the course of this he realizes he needs help, perhaps he can trust you then to be a calm and reliable friend. But you also have some very serious concerns here and you need to keep them in mind first.
It is not your fault that he is acting the way that he is. Sure, you may have some regrets but there are R mistakes that can be discussed. You made the best decisions that you could at that time.
His problems go beyond your R.
But he has to save himself. He is not your job.
M: 16 years Bomb 4/07 OW 20s long gone Divorced 11/09 I remarried New Guy Cooperative r w/X regarding D