Stop talking to her.
File an Item Not As Described dispute with eBay/Paypal - under Help and Contact's dropdown menu--> Resolution Centre.
You will be required to return the item, with Confirmation of Delivery, to the seller. You will not be reimbursed for the return postage.
If she is smart, she will refund you in full as soon as she gets the item back. If she does not, escalate the Dispute to a Claim. Paypal will refund your original payment and go after her for their money. In addition to a the loss of money, she will have a violation on her selling account, she may find her listing fees rise , and it may be more difficult for her to list and sell on eBay in future.
EBay is the venue where you make purchases. Paypal is the mediator between buyer and seller processing payments. They work together.
PP works with many other businesses. In fact, I have used it to send money to family for gifts, so it can be used personally.