Been with my current GF for a little over 5 months now. We have a solid, dynamic relationship, and she respects me a lot. Frequently comes over my house to cook, clean, and sex is very healthy. She is a very traditional Serbian girl (old school), and she follows my lead and listens to everything I tell her. I've taken her on several trips already (she pays for her half 90% of the time, so she isn't free-loading), and I have her come with me on adventures she is not normally used to (hiking, camping, etc), and she frequently tells me how much she loves traveling with me.

She works at my current place of employment in an office setting (I am several levels above her as an office director), and I recently discovered she slept with another co-worker after the first few weeks of working here (6-7 months ago).

Not sure if it's worth continuing anything at this point knowing this information; it's a dynamic that makes me uncomfortable.

Should I suck it up and deal with it because this happened before we were in a relationship, or should I end it knowing how easy she gave away sex to a co-worker she barely knew? I don't care to confront her; it will make me look weak and needy for no reason, and it's something that happened quite some time ago.

Some direction or insight would be fantastic.