Anyone have advice for me

So im dating this boy we're the same age and we have been on and off dating for 6 months now. This is our 7th time getting back together, and today was my limit, he was texting my ex today and was like saying stuff I didnt say and doing stuff, and then he asks him to be friends, im like bro seriously and hes just making my health worse but I don't know how to get out of it, he says he'd kill himself if I left again, and he made me promise I wouldnt leave but hes also very sexual and dirty minded, I domt know what should I do, we're both teens.