Better cheat on him just in case.
Then do it again just in case--you want to stay ahead in this kind of situation, right?
It could be just guilt has arisen it's head now you need to move on from it and if you didn't tell him then i doubt it would do any good to tell him now but still having said that it's your guilt you have to live with...can you...?
you should break up and he is *** for tat first you cheated and now him you should to him
What goes around comes around...
Have an honest and open talk with him. Tell him what you suspect and to encourage him telling it you might add saying you don't mind and you can forgive him if he cheated on you. Don't blame him, don't get mad at him, just encourage him to tell about it and show interest. Of course this means you got to tell him about your cheating adventure two years ago too, but I think he has the right to know and if he's a good guy he'll forgive you for it. Certainly if you feel sorry about it.
talk to him
don't cheat ... in your future ... that's what the dream says
forgive yourself and move on. If you tell him now it will only hurt him.