First try to brush them off saying " Oh, I don't want to think about all of that stuff right now...let's just relax and try to have a good time.
If she persists, you could try turning the questions back on her...getting her to talk about herself instead of answering about yourself. "Oh, my life's so dull right now...just work and the baby---but tell me about your .......
If she still doesn't get the hint, just change the subject abruptly to something neutral like a TV show or something cute your son did.
Try not to get cornered with her...stay around other people, who will hopefully add some distraction to get her off the 1000 questions track.