Should I let it go or is there something that I can do?

I know I seem like a p**** writing this and long read so sorry
First time I saw her 4 years ago at college and something just happened that day, we kept staring ans hovering around each other for a year. I knew she had a boyfriend that she doesn't like and my moral wouldn't let me hit on someone who is taken.
A year later we took a class together and she would always sit around, I decided to start talking to her and eventually told her how I feel but to my disappointment it turns out she was engaged so I decided to stay away from her till I graduate... Her friend told me that she loved me but when I didn't talk to her on the first year she thought I wasn't interested.
Now 4 years later I am already a graduate and I haven't seen her for a year but I can't. Help but think about her.
I had a couple of gfs and mnay girls but still all I can think about is her.
From the first day I saw her my heart skipped a bloody beat and deep down I felt like this is the girl I wanna marry.
It makes no sense, call me an idiot idc but 4 years later after I first day I saw her and she is still the only girl who has my heart. I went through a thousand others in those couple of years just to try to forget her but I can't...
Now I heard she is single again but I feel like I would make an absolute joke out of myself if I tried to talk to her while I don't even have her phone number now all I got is her fb account and we aren't even friends anymore
I know It sounds stupid but I still wanna marry her that's how serious my feelings are
So help me people should I let it go and hope a few years can mend this or should I take a blind shot on a moving train and try to talk to her on fb?
Please take it easy on me I already feel like a piece of shit for loving her after all that time but the heart wants what it wants
Should I let it go or is there something that I can do?
Should I let it go or is there something that I can do?
Add Opinion