We all go through breakups (unless you're super lucky and your first boyfriend ends up being your soul mate). I've never really gone through an "official" breakup, but I do know how it feels. Yeah, it sucks, especially if you didn't see it coming. You feel like you don't know what to do anymore. You start to think that maybe there is something wrong with you and that maybe it's all your fault that something like this happened. You just dig a hole and bury yourself in self pity.
First of all, try to stop doing that to yourself. Torturing yourself with self doubt and self pity isn't going to do you any good. Yes, it is hard and I can imagine the pain that you feel, but you have to get back on your feet. I'm not saying that you can't be sad or upset. It's natural to feel that way. But just don't let that feeling swallow you up.
Most people will probably tell you that there will be someone out there for you and that there is more to life than guys. Although they are both true, I understand that it is hard to accept that now. Everyone keeps telling you that, but nothing in life seems to give you any sign of those statements being true. I get that and I'm sick of it.
But you know what? You're still alive. That means you still have time. Time to heal, that is. Time is great at healing wounds of the heart. The memory of the pain will soon fade with time and you'll see that you'll be all right. For now, go ahead and be upset. Be sad and cry all you want. Just let it out, but remember that time will soon fly by and it will help you. You don't have to go through any of this alone. I hope you feel better soon.