Toxic relationship

hello! I want to start this with what I’m looking for out of this, I would like some advice and suggestions for how to break up with a toxic person anyways I’m going to start on why I need help.

I got into this relationship in November of 2025 and in the first month or so he wasn’t even rude or disrespectful to me in any sort of way that was until maybe the second month he started to say things like “I’m going to k£ll myself if you ever leave me” and I’ll write a letter explaining why I done it and you’ll be the one and only thing on that letter” he would also send me videos of him cutting himself after I came out and told him about my own $h problems and he let my feelings get repeatedly hurt by his friends and in the end up if I ever say on the topic of breaking up with him he will ultimately say he’ll off himself and I’m scared and I don’t know what to do as I’m young and it has gotten to a stage where I cannot deal with it anymore and I have no idea on how to break up with him