How do i get rid of my ex girlfriend?

[That]

She broke up with me, but is now trying to befriend all my friends who she didn't know before we met and made hardly any effort with while we were together. Now we're not together she has started liking and commenting on all their posts on facebook, inviting them to lunches and nights out and it's making my life awkward as I now have a new girlfriend and don't want her to have to be exposed to my possibly crazy ex girlfriend. Is what she's doing weird or am I being petty and over reacting?

[Chyeaa]

It's what us ex girlfriends do. She's getting back at you. Meaning, if you don't want her..then she'll show you who will. Listen to "picture to burn" by taylor swift...she basically tells you why girls act like that.