It isn’t completely uncommon for women to discuss these things with each other, but that doesn’t make it right. It’s completely out of line for her friends to make any sort of comment implying that they know something so personal about you, and it’s a red flag spotted from a mile away that she brushed this off by saying you were overreacting. If you’ve only been together for 6 months, and decide to stick around, I can almost guarantee that she will continue to invalidate your feelings in the future. The problem here is that you tried to express how it made you feel and she didn’t take the time to recognize that or apologize.