<human>: Could you distill the essence of the text into 1-3 sentences?

We started dating in 2011, my sophomore year of highschool. She was a freshman in college at the time.Towards the end I wasn't a very good boyfriend, I even cheated on her once (she never found out). 

After we broke up, I felt free but she was a mess. Now, she's over me and I'm a mess. 

We started talking a few weeks ago (I wanted to get her back), but last week she stopped replying. Yesterday I saw on facebook that she's dating some guy from her work. 

We now go to the same university, but this is her last semester. I'm afraid I'll never see her again when she graduates, and I miss her to death. I know I should probably leave her alone, but I've matured a lot since we ended our relationship and I want another shot! I want to make up for how poorly I treated her the first time and I know we can be happy together. 

I just don't know what to do.
<bot>: I was a shitty boyfriend, now she's with someone else. I miss her and want another shot at being the guy she deserves.