I have friends with mental disorders (psychotic depression, etc.) that make them think like this from time to time. One in particular was addicted to heroin and attempted on her life multiple times, each time failing by mere chance, one time which she happened to contact me, and I talked her out of it. She is sincerely thankful she's still alive today, and she's one of my best friends now.
What you're feeling can be compared to an addiction, like my friend's. When your brain experiences emotion, it secretes chemicals in to the blood stream which bind to cells and make you feel the way you do. This is the same with any drug. Thus, as one can be addicted to heroin, one can be addicted to emotion. What you are experiencing is a withdrawal from love. It was abruptly taken away from you, and you can no longer receive this "hit" which has sustained you for so long. It's natural to feel heartbroken when something like this happens - you've been taken off something which has sustained you in genuine happiness for so long, and it hurts, I know, but it is not the end of the world - it WILL get better.
Your brain is telling you that you need love from one person, which you can't have, and this is why you can't think straight. Give it time, do not make any rash decisions, and find a way to release your emotions. Time heals all pain if you will let it. Be strong, accept the support of your friends and family. Talk to them about it and be open about your feelings. They will help you, trust me.
I find it important to mention that you shouldn't run from your feelings, either. So many people I know have ruined themselves with alcohol (and heroin, incidentally) because of things like this. You have a life going for you, and family and friends who love you and to whom you are incredibly important. Don't throw away what you have. I know what it's like to feel the way you do. Most people do. Talk to someone about it, and let it all out.
