There was a married woman I had a relationship with.
For what reason did you do that?
I didn't know when I started seeing her. She lied to me.
That was her responsibility then. She should know better than to cheat on her husband.
I didn't force her to do anything.
It's truly unfortunate that she lied to you and her spouse. Cheating is wrong and you didn't know. Now that you do, move on and forward and find a partner that is available and honest.