I think I ruined what was probably one of the best relationships of my life.
I see, what do you want to say to her about it?
I'm sorry, I know I was wrong. I've loved you for so long
I'm sorry the relationship is ruined, but you should have thought of what you would miss before you destroyed it. I'm glad you're so remorseful on it, but if you really want to get back with her go to her right now and say you're sorry.
Nah, she not worth it anymore.
I am confused since you said earlier that it was one of the best relationships in your life.   Even if you do not get back together, you should try to make things right.