I don’t know what to do

My boyfriend when he’s mad tells me im fat even though I’m under weight. Says I’m ugly, says that I’m worthless. He also tells me know one cares about me (that’s just some examples) But other times he so sweet it’s just the littlest thing will set him off idk what to do I don’t wanna lose him I just want him to stop saying things in the heat of the moment because it’s making me start to believe them.