<human>: Can you provide a brief rundown of the text in within 3 sentences?

Today could have been the best day of my life. It could have been the one year anniversary between me and the best girl I've ever known. I know I'm only in college, I know we've been apart for 11 months today. So what if we were only together for a month? So what if I'm "too young to understand love"? I'm sick of hearing it. She was and is the best person I've known. I'm still friends with her, but it kills me that she's with someone else. Someone who treats her and me like absolute shit. He's put her through so much torment in the last two months that I don't know why she's still with him, let alone even associated with him. I love her so much, and I can't stop. I can't get her off my mind. She's always the last thing on my mind before I go to sleep. She's always one of my first thoughts in the morning. We can't even hang out with eachother without her getting questioned by her bf. He's started near hour long arguments with her that have left her on the verge of tears, while he sits outside her apartment refusing to leave. She feels "sorry for him" and has him go into her room while she tries to hold normal conversations with the FOUR OTHER PEOPLE IN THE ROOM. He only wants what serves him. He doesn't give a shit about anyone but himself. 

I never treated her like that. I can't understand how terribly I fucked up to make her want to leave me directly for him. It kills me, every time I see them together (which is almost every day of classes, since we're all in the same major). He makes snide comments passively directed at me to tell me to fuck off, that he's won. (this kid is half my weight, barely 100 pounds soaking wet, and built like a sapling) He's trying everything in his power to kill me, and its starting to work. Today is the worst I've ever felt. I don't know how I made it through the day without breaking down, though I came close to it many times... I don't know what to do...
<bot>: depressed over what could have been with an ex girlfriend. The best girl I've ever met. The only one who even remotely understands me in our entire major. The one who I can't get off my mind...