If it is possible, I suggest you leave long before her bedtime!
Let one of her parents read the bedtime story, after supervising tooth brushing etc.
And as Lady MacBeth said: " Stand not upon the order of your going, but go at once."
Don't prolong the agony by saying we can do this and that and then I have to go. Play or talk to her until you are ready to leave, excuse yourself by going to the bathroom, whether you need it or not, and come in wearing your coat, and say cheerfully, "That's me off home now, give me a kiss, see you next week." And go.
Then check with her parents next day. As like as not, she was as right as rain ten minutes after you were out the door.