How do I get my future mother-in-law to back off and give me space?! She drives me nuts!?

FH's sister is staying with us for a week until she moves into her new place. I don't mind, cause I like her, but since this is the case, FMIL thinks this means she has an open invitiation to stop by every day. Everyday when I come home she is there and as soon as I walk through the door, I get bombarded with 50 million questions about my day, which is NONE of her frickin business. I am a surgical resident and I have a lot of stress and I don't need that woman in my face. Last night, was the last straw. I was making dinner and she followed me into the kitchen and asked me 50 million questions about chopping up chicken, which I was doing. She has chopped up chicken before, so why the questions. I finally told her that I had a bad day and I wanted some time to myself. She left, but I think she was hurt. I told FH to please keep her away from me and why doesn't get that I am not a people person and that I need to decompress after a hard day.