Responses
He's being a lying hoe to her just so he could still be with her.
To answer your question, both was correct but at different times. When he said "do you really think I would cheat on you", nothing happened then cuz she left before it did. His wife found out and thought they did "it" he argued back since it didn't happen and he felt a sense of guilt about the whole thing. Now when he says "but I really did it with her" took place two years later from when they first "supposedly would've done it". I hope I cleared some stuff up.
At first he said " do you really think I could cheat on you ???"
And now he says, "but I really did it with her "..
What the hell is going on ???