Boyfriend tries to threaten me with suicide?

Any time we have a heated argument he always says something of which he’s going to kill himself because of me. Ofc I really have no way of knowing how serious he is. He could be saying it to get what he wants, or he could legit be serious. He says if i break up with him the he’s going to go OD or something of that sort. Once he held the box cutter to his throat cause I was telling him to leave. I tried to grab it, he smacked my hand away. He carved the letter ‘E’ in his side (that’s the first letter of my name) and said it was so “we could remember this day”. Lately he’s been really trippy cause once night he was out with his friends and i went to a party with a friend of mine and he basically said i can’t wear makeup unless i’m going out with him. Just last night he tried to tell me if i’m mad at him and ain’t talking to him, I can’t talk to anybody. How would y’all handle this. I want to leave him but I also don’t want him dead either (in case he is serious)