There's a story about a guy finding a poisonous snake in the snow and taking it into his home, putting it in a box and setting it near the heater to get warm. When the snake bit him, he was shocked and asked "Why? You would have frozen to death. I saved you life and now you've killed me." The snake said, "You knew I was a snake when you picked me up."
I have to agree with Josie. Check into an order of protection, block the guy from your facebook, phone, everything, and have no further contact with him. He's obviously delusional, paranoid, violent, and fixated on you. You can't fix or help him. You can protect yourself.