i would say in this case both of you were equally stupid. (no tracking # and gift payment) therefore, i feel that you should split the money.
this could have all been avoided by getting a tracking # to prove that you sent it, that it was delivered, and that it was not lost. even if it was lost you would still be able to prove you sent it.
doesnt sound like a fun situation.
legally, it sounds like you're in the clear. you both sent "gifts" to one another, so she cant say that you didnt hold your end of the bargain, because then she would be in trouble for avoiding fees and taxes
it comes down to what you think is right. if you give her half then at least you made a little bit of cash. then again, maybe she did get it and since you dont have a tracking number she can just play it off like you scammed her
theres just too many variables in the equation to think about. good luck