I don't know how to deal with it. Please help me...

I apologize for a long story.

I am living with my husband and his family. His sister (and her family) is also living with us under same roof...

She interferes in our life. She takes the decisions what to do... at home. Also she is one who buy grocery, clothes etc for members at home. My mother in law also wants her daughter to be boss...

I need a baby sitting but can't go outside because she said she will do better. She pretends to like me in front of my husband but when he is out , his mother and sister don't like to talk to me, they don't wanna share anything with me, even laugh. I'm like living either as a servant or at somebody's home. I'm student and also mom of 1 year old princess. I've no private time. If they saw us talking to each other, it kills them. They want us to be separate. They tried their best to keep us apart. Mother in law thinks I'm taking her son away from her... now I need advice how to deal with this as she is pretending. She pretends to do a care of my daughter in front of his bro but after he is gone, she is like... who r u baby?? I can't expose her to him because he loves his sister so much and I don't want to break his trust. If I talked to her she use bad language. So don't wanna talk to her anymore. Please help me... Thank you in advance...