Cheating means that not only did you lie to him but you are lying to yourself. Happy people in committed relationships who truly care about their partner DON'T cheat.
Time to get real. Why did you do it? Are you happy? Are you content in this relationship. Are you too young? Is he too young? Would you be better off single so you could date and fool around with whomever you please?
Let him go until you get your head on straight. You need to handle yourself before you can even BEGIN to figure things out with him.