I wouldn't have asked if it was used, but stated it in a professional manner that the purse has been used, no tags and is not in the same condition as it was packed.

I would send a message saying you are prepared to refund the purse price only as this one is no longer new.

If she agrees do so, terrific, cut the losses, if not and wants to open a case, make sure you keep all messaging done through ebay and PayPal, sending pictures of the item showing as used.

Many young buyers try one on and give up when they find it's too difficult.

This buyer seems a problem buyer, hopefully they accept refund and add them to your blocked bidders list.