I can't stand it anymore!!!

I live in an addition that’s built onto my grandma’s house. She lives in the front part of the house and I live in the back. My grandma has Alzheimers and I have a 1 year old daughter. So I’m pretty much stressed out all the time. About 2 months ago, my friend and her boyfriend moved in with me. I figured that since she is my best friend that it would work out perfectly. But in reality IT’S HORRIBLE!!! My friend is 4 1/2 months pregnant and she uses it as an excuse for doing chores around the house. All she does is lay in her room all day and me and her boyfriend wait on her hand and foot. When she comes out of her room and she hangs out in my living room, she leaves all her plates and cups all over my part of the house. When she puts her stuff in the sink, she just expects somebody else to wash it. The other day I asked her to do the dishes that were in the sink (95% of them were hers) and she told her boyfriend to do it for her. When he said no, she ended up doing it, but complained the whole time she was doing it. It’s getting a bit ridiculous that she won’t do any house work. I don’t know how much longer I’ll be able to take this. Also, I am expected to buy food for the entire house. She pays $500 a month for rent for her and her boyfriend. She should have to buy her own food. I get food stamps for me and my daughter and with them I have to buy food for everyone in the house. I don’t think this is right. Any advice on how to handle this situation?