TW: SA, NECR0PHILIA, CANNIBALISM

my (16f) ex fp (16m) told me that my best friend(15nb) was into consensual necr0philia and cannibalism. I obviously freaked out and he started excusing it saying stuff like "it's not any different than fvcking a sexdoll" or "you're overreacting" or "it's only weird because society made you think so". I got super pissed and continued to freak out but then he said he wouldn't have sex with a corpse but that's just his views on it. He then asked my best friend (my request) and they said they were obviously joking and that it's disgusting. They got mad(? they said they werent mad) at him for it for putting them into uncomfortable situations because we keep talking about them in a weird context. He then got mad at ME and said it's MY fault for them getting mad at him. I was super confused and I obviously asked him why and if he could hear himself but he kept going saying how even if they were into it it wasn't any of my business and I should stop being so sensitive and that it wasn't such a big deal...I didn't make him tell me about it tho and he just said it himself and his excuse was "I don't think" and I asked him how is that my fault but he didn't have a good enough excuse for me to remember it right now. He then started going on to say "why am I like this why do I always ruin shit why cant I keep my mouth shut" and I just stood there quietly not saying anythng. Obviously upset, he started going "you're the only person I can talk about this with and you dont even care." so I asked him what did he want me to do considering he was mad at ME and was convinced it was MY fault that he told me that just a second ago so he ended up ending the call and going to sleep.

I have no idea what to do and I'm genuinely stuck.