Most Helpful Guy
You are going to have to forgive him in order to move on from that. But it will be very hard to forget what he has done. Technically he was wrong and right for what he did. He was wrong because it was a good chance you guys would get back together. Statistics show this. And he was right because technically you both were not together. But it's an easy cop out excuse. I think maybe with time you can forgive him.
Most Helpful Girl
I know it hurts, but I admire his honesty in the situation.
Imagine, if he didn't tell you and you had to find out through that person.
I think he is a respectable man who cares for you.
As long as he's human he will make mistakes, I don't even think he enjoyed the experience because his heart is with you.
If you find you're unable to get over this, then this is ultimately the end of your relationship.
From this point, you have to decide to be okay with it and never bring it up again.
If you continue to do so, you'll destroy your relationship.
You have the choice to your future with him...