Josh:
My condolences. Over two years
is a long time but the fact that you started dating her at 15 makes the breakup seem inevitable. People change and we change
a lot during the later teens and early twenties.
Still, it hurts. Yes, you'll certainly have other girls and other relationships and yes, you're young but you still have feelings and no reason to apologize for that.
No real advice; just don't dwell on this too long and start feeling like a 'victim'. Get out and have some fun with the guys and what happens, happens.
