Its taking too long

Im new at this, but here it goes...

For the last year and a half of my life ive felt nothing but anxiety, all stemming from the break-up i had with my ex-girlfriend. Before this, i was a seemingly normal person. i hooked up with tons of girls, partied a ton, and had a great group of friends. During the relationship was even better. it was a completely new experience for me, being in love and all. But as time went on i felt like i was too young to be commited to just one person for the rest of my lilfe, and the fact that i couldnt see an end in sight scared me. I broke up with my ex-gf of a year a half just before my 20th birthday, simply because i was afraid of the future. Had i known this is what would become of me i never would have done it. she was heartbroken, but was able to move on eventually. I kept waiting for myself to move on, but for some reason i never did. I met new people, new girls, kept my life interesting, and for some reason she is always there in the back of my mind. i slipped into a depression knowing that i would possibly never see her again, due to where we live geographically. now she is working for a tv station and is on the internet constantly and looks beautiful. and i just feel small and sometimes i just hate myself for doing it. I know i shouldn have waited this long to talk about it, but depression has a funny way of influencing what you do. has anybody been through this before? Broken up with a girl and regreted it the way i have? any advice would help. thanks.