I am sorry to hear that your daughter's relationship wasn't what she thought and expected. It can be a shock to everyone as the person becomes closer in the family. It's heartbreaking but good that it happened before she made a life commitment.
Your quilt is lovely and will be well liked by your new recipient - good that you didn't abandon it and refocused to give another friend a beautiful gift! - a very generous thing to do.
Many of the suggestions will give you lots of options - I like the idea of using a soft gold or a varigated blue/teal.
A black batting should be fine - hold it behind your light colors and if there are shadows and "dark spots" I would switch to an off white or cream color batting.