Should I be upset?

EDIT: We are a lesbian couple.

My fiancé has been friends with this female since high school, and during high school they messed around once, making out and basically dry humping. Her friend is also a lesbian. Well, now they’re just strictly friends. Her friend sent her a pic of her boobs when she got them pierced, this happened when me and my fiancé first starting talking. Basically, I don’t really trust the female bc she’s shady. The other day I was on Snapchat on her phone with her little brother and he accidentally clicked on the girls name and this conversation was there...she asked my fiancé why I don’t like her/why she doesn’t talk to her much anymore.. and my fiancé told her it’s because they have a past and I’m protective and also I’m jealous that she’s known her longer. I feel like 1. My fiancé should have told me about this conversation 2. She shouldn’t have told her that’s the reason why, because it’s none of her business. 3. My fiancé told me the reason she doesn’t talk to her anymore is bc she was a bad friend and wasn’t there for her when she needed a friend. I brought it up and she basically said she didn’t see a big deal about the conversation and that she knows her friend still likes her... So now I’m just confused and upset. Is my fiancé in the wrong or am I just crazy? How do I handle this situation.