Dream of girlfriend

My ex of 2 years (we're both girls) had been dating from someone from outside of state behind my back. The very day the girl moved home my ex left me and started dating her and they moved in together the next day. I was devastated. It still angers me so much the way she went about things and just totally up and left me. He felt no remorse and thinks I'm crazy to even be upset because she says we weren't going to work out anyways. It really hurts. So last night I had a dream that a friend and I went back to my house and my ex and her new girlfriend were having sex in my bed. When thy saw me they laughed at me. They said haha that's what you get. I was so upset and they thought it was hilarious because that's the reaction they wanted out of me. I started hitting her new girlfriend and they just kept laughing. I feel like its real and can actually see them doing this. It really hurts. What does it mean?