<human>: Ages: We are both 17, Genders; I am male, she is female, Length of Relationship: We have been going out for over a year last month.

My girlfriend is hanging out with another guy and it makes me uneasy, while I trust her, I don't trust this guy because he has treated her like garbage. He has called her a slut, made fun of her, made fun of me and my girlfriend and our relationship. 

They have gone out before, while my girlfriend and I were dating, when she didn't realize it was a date and some odd stuff happened. She has a massive savoir complex and claims that everything he has said about her, he didn't mean. They have had fights and several falling outs but she always forgives him for basically anything he does. They have known each other for less than a year, so she met him after her and me started going out.

She says he is a good person but has no reason to think so(yes, she actually admitted that) I have told her how I feel about this but nothing really convinces her that she is being insensitive and annoying. She says he doesn't care how i feel about it. 

I have not asked her to not hang out with him, as I don't have that right. But still, it kind of unsettles me. She doesn't even try to reassure me that nothing is going on. I do trust her, just not him. 

We have been going out for a little over a year now so I am very sure that I trust her completely and that we both love each other in a teenager way. What should I do?

P.S. If any more detail is needed, I will freely provide.

Can you summarize the given text in a few sentences?
<bot>: Girlfriend hanging out with other guy who is a jerk, I'm uneasy about it and she doesn't care at all. What do I do?