Gee, FLTC, sorry you have another bump in the road. It sounds like the issue goes beyond your STBXW saying "ask your father".
Your D17 DIDN'T ASK....she just took your credit card. From previous discussions I might have expected you to say that was your older daughter; I didn't realize D17 would do such a thing.
It sounds like you did a good job taking the focus away from gym woman.