Hi wolf,
That stings, I think everyone in the world feels it at times in their lives. Relationships have to be voluntary, we can't expect relationships to work or not work, it is out of our hands. I don't think this person intentionaly hurt you, and if he/she did, then its probably good you found out now, rather than after you two had gotten more serious. I always like the saying, "Its better to have loved and lost, than never to have loved at all."
Either way, you need to cope somehow. Reaching out for help is not weakness or "giving in" to anything, it just means you need help surviving right now. If you were drowning in a lake would you just silently go under? Make some noise and someone will very likely respond and help you to safety.
Don't hide in your room alone, your bad feelings might fade in time, but you will probably have to face this situation again nonetheless. I think if you reach out for help from someone who is trustworthy(therapist, doctor etc.) they can help with your current situation and help you learn skills so you will be prepared if this situation occurs again in the future. Life will always have its ups and downs, they are unavoidable. We can react to these ups and downs in more and more productive ways though, if we are willing to learn how. I don't think anyone is born with all the answers to all their problems. They all make make mistakes and are guided to better solutions. Don't allow yourself to think poorly about yourself and your life. Ask for help and find things that help you to cope. I like to go for long walks and read the daily newspaper. I play music on the guitar also, sometimes for others but most of the times, just while I'm alone and passing the time. These things are much better than thinking about unpleasant stuff for too long.
I'm glad you are reaching out for help here

I've found these boards to be safe thusfar.
Keep yourself safe!
A.