I feel for you Fancy. Just went through the same thing (last year). After a long relationship, got cheated on, dumped and she moved in with the guy the very next day after dumping me. It sucks so bad, I know. But you’ll get better. A year later I am going out, flirting with women, gettin them digits, back to my old self. It takes time, but you gotta give it time. There’s nothing much you really can do except just hang in there and in time, you’ll move on and find another (or two or three ).
EDIT: Also, something else that helped me. After my breakup, I found that when I left my house (she was living with me) I would mostly be fine when I was out (at work, etc.) but would get depressed when I got home. Then it hit me, all this shit in my house that reminded me of her, of our relationship. Like the comforter and sheets she picked out, pictures, dishes. All this shit that was part of our relationship was reminding me of it. So I went out and bought all new stuff to replace this, got rid of anything that was a part of our relationship. I found that helped immensely, not having to come home and constantly be reminded of her. Not sure if it will help you, but it did me.