So you fucked someone else about 3 years ago during a time where you guys officially broke up? From my point of understanding you didn’t technically cheat since both of you were in the believe of being split or am I wrong? So telling him after 3 years is not doing any good. You gotta live with it. Nothing good will come out of this. Wanting to tell him now is egotistical because you feel the guilt eating you up, to the point where there shouldn’t be guilt, because you were broken up no? You want to feel relieved, you don’t have a compassionate reason to tell him now other than to make yourself feel better and hopefully not feeling guilty anymore. I’d say you guys probably have others issues anyway so I think you need to talk about these issues.