I wouldn't have apologized. Having been in situations like this .. she brought it upon herself, trying to pin you against the wall about one friend you had feelings for a looooong time ago. But she's still friend with her exes? Nice.

No shame in having a big body count. No one's who they were in the past. But she shouldn't have tried to make you feel some kind of way for having someone as a friend still. It's stupid. Social media is stupid.