Search Results: he ignoring my facebook request

This girl was in my college since past two years, but, I gained interest in her recently when she started showing interest in me. She used to complement me about every small things. It was more of a flattery rather than complement. I started liking her and I too complemented her as much as possible without being fake.
She was an interesting person and nice to talk with. I tried to do some mild flirting with her, but she never responded to my flirting. Sometimes, she acted really wierd. For instance, once I asked her on WhatsApp if she is on facebook, and she said yes. When I asked her to add me as a Friend, she din't reply at all. I felt that I am being made fun of, so I started ignoring her. With the span of time (about 3 weeks), my interest in her faded.
Today, when I checked my Facebook account, I found that I have recieved a friend requst from her. I didn't respond to it yet, but I am really confused about what to do with it.
Should I
1. Accept her request... that would mean giving this relationship a chance, and being vulnerable to emotional damage.
2. Decline her request... that would make her piss off real bad, and she would never talk to me again.
3. Let the friend request rot in the notifications menu for eternity.
Please help me, I am really confused. :/

BTW, she is the kind of a girl who has the looks of a goddess, but is too insecure about her own self. All her selfies look amazing but she never shares them on social media because she thinks they are not that good.