Why do I still dream about my ex? Can we still be friends? Should I move on?

My ex and I went out for 3 weeks. We really liked each other. I found out he was going out with this guy for about for years and when we came over to his house one night his guy friend were getting frisky and giving each other s. I got really pissed. He said they were joking around. We argued for a few days. Then I broke it up with him. He refuses to speak to me. I am having a hard time finding closure. This happened a week ago. He was the only friend I had. Now I don't have anyone to hang out with. I am very lonely and I still have dreams about him. I wish we could make amends and become friends again. But my life kinda sucks so I wish I could fall into a deep coma or just die.......