I don't know what to do

Hi I'm looking for some advice. I was with my abusive partner for a year however the abuse was verbal and physical but he did stop after a while. He cheated when I was pregnant because I pushed him away due to my hormones. I let him be there for his sons birth but recently he hasn't seen his son for two months because I won't let him due to the fact he smokes weed and takes acid (LSD) he's so suicidal and has horrid anger problems. Me and his parents think he may have a personality disorder or maybe autism. He gets extremely paranoid as well. I've tried telling him to get therapy and so on but he says I'm the bad person on all this? Should I let him see our son? When he should be seeking professional help? I've tried helping him for a year but I'm out of ideas since I've put my efforts into taking care of our son. I tell him all the time the door is open to see him but he says I'm blackmailing him.

I just don't think it's a good idea for there to be contact when he's on drugs and his mental health isn't good.

Can someone please help?