From my perspective, one (especially a guy) doesn't get to "I love you xo" simply by kissing and talking.
Making assumptions isn't going to help you. You don't know. You may never know.
In my mind you are too focused on the details of what she may or may not have done. Given that she is in some kind of affair, what are you going to do? She's not going to stop just because you want her to. Exposing it as you have done may lead it to end, but it still could take time. You can't control that. So, what do you want? What are you going to do?
