Most Helpful Girl
I think you already know what she's up to. She's trying to upset you and make your life a little bit harder. Why not? She hates you, right? When my marriage was falling apart, we used to do stupid little things to each other for that exact reason too--he put a chair against the door to keep me from getting inside when I left one night, so the next day while he went out to smoke (he'd promised to quit when we got married, THAT never happened) I locked the patio door, and left the apartment, locking the front door too. ENJOY.
Don't fall for her trap. Get off her twitter and Facebook and move on. Not to a new relationship, obviously, but join a Meetup group or something. Then post on YOUR twitter or fb about what a fun time you're having so SHE can see it, while she changes diapers.