I cheated on my wife...
Why did you cheat on your wife?
I'm in love with someone else.
You need to tell your wife that you are not in love with her and you want a divorce. Cheating on her before telling her this is even worse.
I will marry the woman I cheated on my wife with.
It was wrong to do this to your wife without letting her know at all. Be honest with her if you fall out of love and don't cheat.