How?!

Someone told me today, that I need to move forward. This person told me that I need to let go of my past. What if my past is the reason my present exists? What if my past is the reason that I exist? I don't know how to go on, when the one I love--above all others, is happy that I am not a part of his life anymore. I feel despair; I feel like I've hit rock-bottom. There are too many clouds in the way. Too many clouds, and I'm blinded to the sky above. Although I feel like it would show me nothing but an expanse of bleak-blackness, if I could see it.
How can he do this to someone he "loves so much"?
I can't stop loving him.