Who is overreacting?

My boyfriend and I got into a bit of a heated argument about my mental health and depression. It ended with me upset and him mad at something I said because he insisted that he wasn’t mad AT me. Just that I had said something sarcastically (and no it wasn’t mean towards him) and because I self harmed commonly a few years ago (now like 1-2 years clean with a few slips here and there) he told me that if I self harmed or did anything stupid that he would break up with me. Like his exact words were “Any self harm and we are through.” And I get that he just doesn’t want me to hurt myself and he’s just looking out for me, but I’m not sure how I feel about him threatening to break up with me if I had done it. Am I overreacting?