Current ltr

Previously just fwb but supposed to be exclusive

Strongly suspect she slept with someone else while fwb

Got a minor trickle truth out of her when it happened

I came to the conclusion at the time that she was just a fuck buddy and so it didnt matter but things eventually escalated into a relationship and it slipped my mind until recently.

Now that we're dating should i even bring it up? and how would i even get the truth out of her? We were supposed to be exclusive which is essentially a relationship anyway, so it would count as cheating