Am I doing the right thing, breaking up with her?

So I am 23, she is 18 and I've found her to have anger problems that not only I have noticed, but her family and friends. She actually was thrown out of her parents house a month ago because of her drunken screaming and hitting.

She has gotten drunk and hit me with a random piece of wrapping paper, it got right on the nuts, it was over someone so small neither of us can remember it.

She will never admit she has a problem, or when she is wrong. She's much younger than me, been together for one year, but I broke up with her because of these reasons. I need a calm bit older girl.

Now the odd thing is she still lives with me, in another room, and I refuse any close interactions with her, being a 'hard-case' so to speak, treating her like another room-mate.