Should I Tell His Wife?

Stop seeing him and make it clear you're making this decision because he's moral slime and lied to you and his poor wife. Of course a man being a man, he may well come back saying he's finished with his wife and still wants to be with you but don't be taken in because this guy wouldn't know the truth if it bit him somewhere naughty! I wouldn't go out of my way to tell his wife because that's sinking quite low but do not lie for him anymore.

You were mislead, for too long, so it was not one of those things that just happened in the heat of the moment; he should come clean with his wife and you should most definitely step out of the picture; letting him no that you have decided that this is wrong and that he was wrong to mislead both you and his wife; you really need to think about what kind of person he is and believe me i have heard all kinds of reasons as to why they cheat, when really there is no exceptable reason other than the male instinct to do so; i do wish you the best with this, make sure you do not comprise the person that you are for a guy that is very deceptive; i am not meaning to sound harsh but you really need to take time an analyze this before you continue on.

You need to break off this relationship yesterday, and no longer have contact with him. Then in about a week or so, I think that if you have the values that you say, then tell his wife, as she has every right to know about this. He has broken her trust, yours, and lied to more than one person in all of this I am sure. Please do the right thing here.

I may not tell her right away,like tomorrow,but I would stop seeing him and would think little of him for misleading me.

I would stop seeing him for the fact he concealed it from you... Not to mention if he will do this to her what would he do to you??? Yes tell her! Comparing his lies is just gonna make things bad for the two of you so just tell her and leave it at that.

Break up with this guy and stop seeing him.  I don't agree that you tell his wife. Why involve her in what happened between you and her husband?  She has nothing to do with it.  Move on with your life without hurting his poor wife whom he cheated.