Prob with Paypal!! what happens with a negative balance???

A buyer put a dispute on paypal i replied offered partial refund but she wasnt happy escalated it to paypal and they granted it, but now im told someones destroyed the item sold so i cant get it bk so ive lost more money.. and paypal have refunded her 150GBP and wants me to refund a further 82GBP.. My account now has a negative bal of -150 i dont no what to do.. What happens if i dont sort the 150 out or the refund?? ive said im not refunding all as shes not returning the item please help...