Would you be annoyed if your friend did this to you?

[Leanne]

Some people compartmentalize their lives. She's met a new friend who comes with a ready made set of other friends, so perhaps feels that you belong to a different part of her life, or that you'd feel out of place with all these people. We tend to get different things from different friendships and she might have discovered a new aspect to herself that she can be when with these people - different to how she is with you, which might make it a bit awkward if the two are brought together.

I dont think you're being silly but I dont think there's any need to feel let down. She's just reinventing herself in this post-divorce stage. Perhaps suggest that you'd love to meet her new freinds some time but otherwise just enjoy the times you do have together. You're her long-term, close friend; these newcomers have no shared past with her so no one will be able to take the special place you occupy.