firstly, and most importantly, did you send to the address given to you by Paypal?

if yes and it obviously had to be signed for, then if she opens a dispute in paypal for non receipt you can prove that you sent it and it will be up to her to pay you agian to ''resend''

if however you sent to anothr address as she may have asked you to do.... you are not covered by paypals  SEller Protection,