Trying to remember the title of a movie about a college girl..?

I really want to rewatch this movie I haven't seen in a really long
time, but I can't remember the title of it. If anyone can help me
remember a movie meeting this description, that would be great!

From my limited memory, I remember it being about a college girl. she
had a lot of psychological problems (she was mentally ill). At first
when she went to college she had this roommate, who was a pretty good
friend of hers, until she backstabbed her. I think she had oral sex
with the guy her roommate liked at a party (by the way, this movie is
rated r). Anyway, this girl got into a lot of drugs and alcohol, and
pretty soon, her friend realized she was crazy and didnt want to be
friends with her anymore. Then she met a guy, who she thought she
fell in love with, and this guy thought he loved her but then I think
he realized he was mentally ill too... and they didn't see each other
anymore. Eventually, she moved back into her mom's house and
continued to abuse drugs there.

I remember this movie being really good, and it's driving me crazy I
can't remember the name! Sorry for the long description.. hopefully
someone can help me! Please and thank you :)
This movie came out a while ago... it is not "The Roommate".