my mother in law still lives with us I'm going insane?

[selenafanalways]

MY mother in law has been living with us for 4 yrs. She does help around the house. we tell her she doesn't have to but she says it keeps her busy. We don't charge her anything to stay with us we buy everything ocassionally she does too. She shares a room with my 10 yr old daughter. I feel she needs her own room it's not the same sharing with grandma she can't have her friends spend the night, We have a duplex our upstairs apartment has is empty we suggested to her to move upstairs mind you she doesn't have to pay nothing but she won't we have suggested it but she says she can't climb the stairs. But in her old house she did have steps to climb she had no problems. I hate living with her i have no privacy it's just not the same when you live with someone I won't expect my husband to love with my parents. He feels he's in the middle Most of my friends don't come over because she gets an attitude I need advice. My doctor has increased my depression medicine because of this.