Girlfriend had a friends with benefits that she told me she wasn't talking to, but turns out it wasn't true. Am I being stupid here?

Anonymous
Me and my girlfriend work and met in the same store. She told me once we started dating that she used to have a friends with benefits that she didn't talk to anymore.
After 1 year I found out the old friends with benefits was another coworker, and she told me that she decided not to tell me because "what good would it do".
They were still in contact, and when she said "they didn't talk anymore" she ment that she didn't knew where he lived now etc.
I found out who the old friends with benefits were through another coworker.
I feel kinda bad that my girlfriend wasn't open about it, and decided that she would not tell me.
Im not sure if Im being too much, but it just hurts and I feel like I can't trust her somehow.
What are your thoughts?

PS. even though he quit, she invited him to our Christmas party, and was laying her head against him while I was there looking at it.
Girlfriend had a friends with benefits that she told me she wasn't talking to, but turns out it wasn't true. Am I being stupid here?
4 Opinion