<human>: So my best friend (Let's call her Rose) has been in a relationship with this guy for 6 months now and I'm really worried about what it's doing to her. 

I met Rose at the start of the year when they just started dating and for the last three months we have been really close. The thing is though, her boyfriend is extremely possessive. He gets angry every time Rose and I hangout because apparently I'm trying to 'take her away from him'. His behaviour turns threatening, and he starts saying that he's going to cut himself if she won't talk to him and sends pictures to her of him cutting his skin. Other times he'll show up wherever we are; for example we'll be at the beach and he will come when he hasn't been invited. He doesn't let her hang out with me at school and also decides who she can be friends with. He decides what profile picture she's allowed to have, what boys she can talk to and where she can go. If we do go somewhere without letting him know he instantly accuses her of cheating on him. He's also got an anger problem and gets in trouble with the police quite often. She gets really angry with him a lot but each time he apologises and said it won't happen again. 
Rose knows that I don't like him and she knows I think their relationship isn't healthy, but each time she says things like 'but he's not like that all the time' or 'you only hear about the bad things'. I'm really stuck on what to do because she's 15 and this relationship is way too serious for someone her age. She's aware that this is a high school relationship and isn't going to last but I don't think she realises how bad it's getting. I'm worried for her mental and emotional health, and she often says to me that being with him tires her out. 

So my questions are:
Is this some kind of abuse?
How can I make her see what I see?
How do I do this without hurting her?

Side note: I'm 14F for anyone wondering. And yes I know we are in high school and these relationships are stupid but that doesn't make the issue any less important.

Can you condense the text into three sentences or less?
<bot>: My best friend is in a relationship with an extremely possessive and controlling guy and I'm not sure how to convince her to leave him without hurting her.