My son was the 'difficult one'. It's awful. But i know it was awful for the other mums too. After all they want to protect their children first and foremost. He is/was different to the little girl you describe, but still a handful in his own way. I would always acknowledge it though, and never pretend to others that it wasn't happening.
I can't tell you what to do because each situation is so very individual. But i do think that if it was me, in my shoes, i'd know why you suddenly wanted to meet sans kidlets. And i'd feel embarrassed. But, it would still be nice too. I think we all know children go through stages and phases, and it's nice to know that we can still have mum friends who don't judge us too harshly or want to cut ties altogether.

Hopefully you can keep being a friend to her, but you'll know when it's the right time to reintroduce the kids to the mix - or not at all. FWIW my son was a super star today and played for nearly 2 hours without me intervening once! It was amazing, and we both went home stress free and happy.