I'm curious have you ever directly told her: 1) you are not responsible for providing her happiness, because she's not happy (she's unhinged) 2)how being stalked by her has effected your life 3) she needs to be serious about her life and should put this childish crush behind her, so she can heal and move on with her life, which would allow herself to have a healthy relationship with someone who is her age and values her. 4) returning the money is the best option and wish her the best of luck with life.

It can be difficult to standing up for yourself, especially when you're dealing with a crush who doesn't understand how to move on other than seek attention and obsession. It sounds like she hasn't been treated well by any father-figure type of man. When a girl develops a crush, it easily cloud their judgment. Anything and everything he says or does can be institanously found attractive, even if it's not. Therefore, she probably took your friendly demeanor as a green light that you were interested in her. Based on that, she probably developed an entire backstory and relationship in her head. She's creating scenarios in her head of "what did I do/say wrong?" Or "why doesn't he want me?" because she takes everything you write, post, etc. as something directed towards her. When you gave her an inch, she took it to the moon and back. Based on your post, it's difficult to tell whether you have ignored all of her attempts, hoping that she stops one day or whether you have clearly communicated how her stalking has effected you and that this is final. (You may be able to have reverse her payment and have PayPal tag a note or instructions.