Hello , I am sorry that you were hurt. People don't often behave the way we want or expect them to. You stated that you are no longer in contact with him, I believe that is a good thing, despite the fact that you may want some closure, trying to maintain contact would likely only hurt you worse.
It is sad that your first affair ended like this but we often don't choose who our heart will love, but we can choose to learn from our experiences and we can choose how we greive.
You will learn to detect any warning signs in your next relationship and they will be a next one.
I know you may feel overwhelmed by losing him right now and it may not seem that things will get better but believe me they will , the heart is extremely resilient.
You need to do things, go places, talk to friends that will take your mind off of your ex. It may seem difficult to move and you may not want to. but it is the best thing for you, call up a friend, take a walk, see a movie. Do something! If you just stay home you will just grieve. Soon as you start going about again, it will start getting easier. Tell yourself you will not think about him for 2 hours and spend that time on something that you enjoy or you could pick up a new interest or sport. The next day it may be 3 or 4 hours and so on.
Remember the fact that he treated you badly reflects poorly on him not you and the longer you spend crying over him the more power you are allowing to exert over you. Ask yourself whether you want the person that you now know he is to exert any influence in your life.
If you find that you still cannot bring yourself to do anything, still feel depressed with no energy, appetite or have difficulty sleeping or ideas of self harm you may want to see someone because you may have depression