I'm with denu on this. We're all adults here and we are responsible for our actions. And as adults we know when the brattiness is completely out of line, as it sounds like it is in your situation.
There's lots of ways to handle the situation and several have been suggested and I'll throw in my 2 cents.
A) Establish your space and your time where she CAN'T interrupt you and if she does then set up consequences. And then stick to them!
B) Give her things to do while your working. One example: 10 min masturbation 50 min cleaning until your done. No Cumming! and then when your done, or when you take a work break you can have play time.
Just a couple of ideas.