Most Helpful Girl
I think it's fair if they were expecting you to all hang out together, because that's not very considerate of either of your feelings. But if her friends were hanging out with her exs without you or her present then that doesn't seem fair. If they're not bringing that person into your lives then you have really no right to dictate who they can be friends with.
I'd just make sure to get your partner some friends, because everyone needs friends to hang with, after a while their could be problems in your relationship because she's become too dependent on you or just bitter about not having the active social life she used to have.