My PITA Co-Worker

I'm sorry but I need to vent or I will explode. My co-worker is my such a PITA. First she is my boss' MIL( why would she bring her here?) Second she is just useless. She brought her to the office to help us out with the 'paper work' in the office and she's been here almost 1 year and she still does not get it. I've tried so many times to explain the simple things she needs to do and still she asks questions!!! I'm ready to pull my hair out. She's an elderly woman who is very closed minded and is very critical of everything we say and do. Like when I check out a cuttie she'll say 'Why are you looking at him, aren't you married?' Hello, I'm married NOT blind!! She is just so annoying!!! I have nicely told my boss about her MIL & she just says she will talk to her and never does!! Does anyone else feel my pain???? Please people give me some ideas on how not go postal on her