Kitty Pryde is referring to a really old X-Men adventure where Emma Frost, who was still a villain that time, managed to capture the entire X-Men barring Kitty Pryde.
I like the way Emma Frost was completely honest with Kitty Pryde here. It’s not every day the White Queen lets down her defenses and allows herself to be vulnerable.
From – Astonishing X-Men Vol. 3 #2