Why does my ex boyfriend keep on coming back?

MintyX
So, I am 22 and Belgian and my ex boyfriend is 28, he is Italian and we had a relationship for almost 3 year (two years I think if you take off the time when we've had a break). I will begin with our start. In the beginning he was really sweet, funny and a gentlemen. But he was always super jealous because he thought I was too pretty for him and he said that he thinks al women are whores when the boyfriend is not around (yes I was blind). Anyway, so always if a guy looked at me he made fights and exaggerated so much. This became worse with the more time that passed in our relationship. He also didn't study, also didn't want to study, but always complained that he couldn't get a better job and so reacted his stress of at me by snapping, insulting me, screaming at me and treating me like garbage. This continued until 1 year in our relationship. I was sick of it and started to scream back at him and then fights got worse. I just wanted to be calm and communicate quietly and calmly if something was wrong, he promised me like 100 times to change, but he never does. He also broke off with me like 12 times, we've had 2 breaks but he keeps coming back and changing my mind with his smooth talks.
I have to be honest that I cheated on him 1 time after 1 year and I told him ( while he tried to fuck my best friend) and he keeps on telling me I am a slut and I am not worth nothing.
He also expects from me to shut up, stay quiet and respect him while he has one tantrum and screams for one small problem. But I don't do that ofc.
I don't know if I am the problem of toxic one or him, I would just like to know if this is normal behaviour and why he keeps coming back for me

Small note: he was my second boyfriend, so I don't have a lot of experience
Why does my ex boyfriend keep on coming back?
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