Reading this and the earlier post this seems to me like a clear cut case of someone not having the balls to breakup.
Probably also monkeybranching.

You are obviously tired of you relationship since a while already (who's to blame for that is another story and a long talk about responsibilities in a relationship but that's not for now).

I do not know why you did not end it, whether it was being still a little worried that it would turn out to be thewrong decision, or that zou did not want to hurt him, or that you want him emotionally but not sexually, or something else.

So, when struggling with the decision of having one thing or the other you did the immature thing and decided on having both. As you said entirely selfish with disregard of his feelings.

There are no people in this world without flaws, the thing is to find someone that is willing to work on their and your flaws TOGETHER.

You have two options, let him go accepting to lose the things about him and your relationship that you are happy with or GROW THE FUCK UP.

Bonus: As other pointed out. "I am a bad person and I wanna do this for his sake, he deserves someone better for him". Is almost never that. And even if itx is, he will surely not believe that.
Phrases like that most often come from people who still wanna tell themselves that they are "good" and that they think about others while in truth it is all to get rid of their own guilt.
The motivation behind it is as selfish as the one behind the cheating.