Exo,
You need to forget about him. He is not doing your self esteem any good. One of my friends was in a similar situation last year. She kept taking him back. When she found out he was also cheating on her she was heart broken, lost 2 stone and is now getting counselling. She couldn't see what everyone else could see. When she was with him she was turning into a crazy woman. She has since meet an amazing man and started college at the age of 40. If she was still with the 1st guy I dread to think of the mess she would be in now. It took about 6 months but it was well worth it.
You need to let your ex go. If he loves you he will find his way back to you. The best way to find that out is by letting him go completely.
Be strong. Pick up a new hobby. Get support from your family and friends.