/feels/ - Advice & Venting

So basically my boyfriend is kind and loving but his gradually began talking to me like shit more frequently and over silly things. I would not be worried but sometimes when we fight his began doing things like push me or i tried to leave his mums house once to cool off and he grabbed me by my hair and shoved my face onto his bed so i couldnt leave, but this is kind of an isolated incident. im not sure if it is going to begin happening more often because his begun hitting or throwing things when he gets angry. We got into a fight about a month ago and i said i wanted to break up not cuz i wanted to but cuz i felt it was the mature decision but he threatend to kill me. im not retarded and i know these are red flags in a way but do you guys think its just heat of the moment anger in like isolated incidents or should i be worried? he never use to be like this and his dad beat his mum growing up so i really dont expect behaviour like this from someone who grew up seeing that but idk because im scared in the future it wont just be hair pulling and threats and might become serious. when it comes to the way he talks to me he kind of is just apathetic and mean then will become super loving and misses me so i just feel confused. i feel like his turning into someone i dont recognise but i love him so much, more than anyone ive ever loved before. i will probably talk to him about this and mention him turning into kind of a shitty person when his mad so i can combat the issue before it gets bad but i just am posting this here to ask for opinions or advice because i feel a little lost.