Have you ever cheated or been cheated on?

This is hard to talk about without being judged but I have been involved in Gang Bangs and cheated without knowing it.

Let's just say sometimes guys get involved that are cheating and don't tell you so you don't know that you are cheating with them and it's not always easy to keep track of who's coming and going.

Then their girlfriend blames me for it. How does that work?