Advice

So i need help on figuring out how to leave. i’ve been in this relationship going on 3 years, and ive been cheated on the whole time. ik i should’ve left then, and i did, but i just could never stay gone. he’s a really good manipulator and liar and just knows how to make me feel shitty. well he says he’s not cheating now. but i gave up on the relationship and was talking to other people for almost a year and he seen it in my phone while i was asleep… now he holds that against me like i’ve ruined everything and he was being loyal apparently and now i don’t do anything for the relationship. even though he ruined it with all the cheating he’s been doing through the whole relationship. ik im wrong for cheating back, but i really want out and everytime i get mad enough to leave he just talks about how we will fix it and do better and i just can’t get the strength to let him go or block him and not feel bad. i just need advice ik i deserve better and it’s so toxic. we argue literally everyday and he accuses me every single day of another man being around and such and i just know he doing stuff deep down i just have no proof. why would he randomly decide to be single now after he’s cheated on me countless times the whole relationship? i just need some advice on how i can leave and also why can’t i ever get mad enough to go and not feel bad? ik it sounds dumb, but i don’t know why ive been finding this so hard when i know i don’t wanna be here and would rather go talk to new people.