And I just stared at the computer monitor the next thing I knew...  

Give yourself some time to get a grip, then you may come to your senses and see that waiting for her may not be the wisest choice...it is not your fault, what your friend did, but it is your choice where to go from here.
good luck.

Okay, here's the thing. I'm not going to say 'I know how you feel' 'coz I don't. I'm not saying that my life has always been a bed of roses. Of course, I've experienced heartaches, too, but that's a different story. Anyway, I know that you will get over that feeling, too, and I hope that it would be sooner than later. There really are people whom we call or even consider friends, but in situations like this, somehow, would turn their backs or 'betray' you. I guess you just have to think about something else, think 'happy thoughts', to lessen the pain. Since you mentioned that you're still studying, why not focus on your studies a bit more and surround yourselves with other friends and people who love you, like your family.
There's nothing wrong in venting it all out in a forum or discussion board like this because there are people who has or is experiencing the same situation as yours, and could help you in some ways or could just listen to you, and not judge you in any way. Besides, we don't personally know each other here, and that's one of the good things about this. No one will call you 'loser', and hey, I don't use that word and I don't believe in it either.
Going back to your situation, if you think that you can still wait for her, go on ahead. It's always your choice. No matter how many people give you advices, in the end, it'll always be you who should decide for yourself. Just make sure that you'll be able to handle any decisions you make.
Enjoy life, taki. Take care and God bless. ^_^

Dude, just take it slow, and calm down. Not your fault at all. People make mistakes and are careless when in love (talkin bout your friend) Not to say that this is an excuse, he should have controlled himself.And if you guys promised each other for a long time ago, people change, their ideas, and whatnot.
If he knew that you like her there would probably be 2 emotions coming from him (regardless of the promise or not, those are just words)
1. Jealousy
2. Happiness And from these 2 emotions, there are 2 types of each

Jealousy A. Your friend (thinking to himself): Oh you like her, hmm i better get a girlfriend myself
Jealousy B. Your Friend (thinking to himself): Oh you like her, i like her too, we'll compete

Happieness A. Your Friend: Congrats on liking her (or w.e) hope you 2 will be happy together
Happieness B. Young Friend: congrats on liking her, so stop bothering me with your problems (although this is not likely)