My best friends boyfriend is a jerk!

My best friend is dating this guy for about a year and a half now and he's a total jerk. The way he speaks to her is so disrespectful and rude. They argue about any little thing and he has cheated on her 3 times thru social media. She's caught him in so many lies. I'm the one who hears her crying and try to console her from me to time. But I've told her many times that she doesn't deserve that. Her excuse is she loves him too much. But any time they're together they have sex or argue. I feel like she's attached because she lost her virginity to him. 
What should I do if she doesn't take my advice?