He completely broke my heart where do i go from here, how can someone just change their mind over night?

Clearly this is what he does. He sets up a profile meets a nice girl he woos her, treats her like a queen makes her love him, has then when he's got what he wants he dumps them and goes for the next victim. He is a serial philanderer. He's only interested in the chase once he's landed his catch then he doesn't want to know. He is a cruel and nasty human being and will end up alone. I don't think you were being a bug a boo, he encouraged you making you think he loved you as much as you loved him. He needs to be taught a big lesson and will get his comeuppance. You will have to put this down to experience. Don't contact him again and take his number off your phone. He is evil.