Why is my exs current "girl" still adding me on Facebook?

[Kelsey Marie]

So my ex's new girl, I wouldn't even call her his gf because I don't think it's even official sent me a friend request awhile ago. I accepted it bc I don't really care then the next day she deletes me. I find it very strange. it's been practically a year since we broke up, things ended badly and when we did break up he began to beg for me back. I denied him of course, we didn't talk for a while. We hooked up one time after he'd been blowing my phone up for months but that's it because I found out he was supposedly seeing this girl and I think she found out but I had reassured her it meant nothing to me and I was done seeing him. On top of that her and her friends would go to the same bars as me and try and trip me and be very petty when I'm out, then when I would confront her over the issue she would say she had no problem with me. It's just the weirdest thing. She even offered to get my drink for me when the bar was crowded! It makes no sense. I really could care less of him and everyone knows that, I'm just a bit confused of why she even sent me a request after I accepted it and she deleted me once. I haven't responded to her request for over a month and she just now went on, canceled it and re sent another one! Like what? I haven't even spoken to my ex? facebook is facebook to me, I kinda want to add her to show her that i'm not threatened, I just need another persons point of view.