Yeah....hang out over Christmas if it works out....she wants to hookup...she misses what it feels like and knows it will be comfortable with you. So give that to her and have fun together, but don't let your mind play tricks on you, it is nothing that will last. More like a last hurrah. Don't don't don't don't profess any feelings or pine for her. That is the worst thing you could do and will only validate her feelings to leave you. Instead play cool, show you are happy upbeat and have fun with her as if she was anyone else you'd hang with.
Trust me....learned that lesson the hard way long ago.
After Christmas cut her free and stop feeding her need for validation.