How to move on after 4 years?

I'm 23 and just getting out for a 4 year relationship. It's REALLY hard. I wasn't really the one who wanted out and I love this guy more than anything so I'm struggling. I gave and did 100% and to not have that be enough is absolutely heartbreaking. It's even more heartbreaking to know that he's going to move on so fast. Him and his friends are 22 and in their last year of college and are always with lots of girls. So the minute I'm gone he'll be out with the next girl completely unaffected by the break up. I'm lost and so sad and don't know what to do. I was part of my life for over 4 years and I don't know how I will every find anyone I'll love as much...advice and encourgaing words would be appreciated