My boyfriend threatened to break up with me because I told his mom he cuts?

Guys I'm crying so much I don't know what to do I've known my boyfriend since I was 10. The past few months he's been acting different. He watches videos of fatal disasters and situations like bridges collapsing, people drowning, shootings, found videos of people getting decapitated on the dark web, and would constantly write down ways to kill himself quickly. And yesterday we had sex and he refused to take his shirt off which was weird to me. When we finished he got in the shower and I walked in to give him a towel and I his arm was covered in cuts all the way to the elbows. So when he went to sleep I rolled his sleeves up and took photos of his arms. Then I texted his mom everything and sent them to her the following morning. My boyfriend wasn't at school at all earlier today so I called and asked his mom what was going on and she explained that she was taking him to a therapist. About an hour after that my boyfriend called me and told me that I suck, that I broke his trust, and that he never wants to see me again. I've blown his phone up so many times today I can't believe after everything he's done with me and it's all my fault