Hi, I really feel for you, I had the exact same problem last year when we were living with my mil and I see everyone has said you have to set boundries but it is so hard when you in that situation. Especially because it's their house and you feel obliged to do what they ask even if it is unreasonable. I hated it and unfortunately I couldn't fix it, I told my mil that I just was too busy and tired to do all the things she wanted and she did stop asking me to do things but she just *****ed about me to everyone and even though we moved out we are still having problems and when I talk to my husband about it he just gets angry and upset with me, saying it's my fault.
Sorry I don't have a good answer, but maybe your mil will be different if you talk to her.
Good luck