Mother living with me has Dementia

Hello Everyone, I recently had my mom come live with me, her choice. She was living by herself up until last Oct. Fell Broke her hip, end up in rehab for 2 months for thearpy. When she was in there my brother sought out Gaurdianship over her. Needless to say when she found out she was mad. She wanted to go back home, but the rehab center said no. So she had a choice either me or him. She chose me. I've been looking after mom for 14 yrs after my Dad has passed. He has not been in her life, neither has my sister. I tried to have mom put me P.O.A over her along time ago. But unfortunally she would not, said she didn't need one. So after she had fallen a couple of times, needless to say it didn't help much with her Dememtia. I've taken care of people in the past for other people that has had this type of disease. They were living in there own home, or with a daughter or husband. But I was able to get away from it. Now I have to deal with it on a day to day basis. My mom fights me over getting a shower. Rehab had the same issues. She fights me over taken her meds, not everday and night. But most days she does. She has sundowners really bad. Goes to bed at 8:00pm at night, unless you make her mad then it will be 10:30 or 11:00. I give her mood stablizer pill at night as it say's it causes drowness. She will be back up at 4:00am. If I give her the pill in the morning, then it knocks her out most of the day. And then she is up all night. And I don't go to bed until 12:00 or 1:30. So I'm not getting alot of sleep. My brother dosen't help, but he wanted gaurdianship over her. I've got a sister and all she wants to do is call on the phone and ask how she is. I myself have been thru alot. Horriable metal abusive marriage for 36yrs. And then a yr ago in Oct God called him home. I had to move myself to my new house I bought, as my old house belong to inlaws. I joined a church, was going and doing activies at the church. Plus attending services. I was finally starting to get happy. I had a new house for me and my fur kids. And now I can't do anything. Mom dosen't want to go to the grocery, Doctor's, or church with me. And she can't be left alone even though she think she can. She has always been stubborn,and very contray and needless to say the Dementia dosen't help any. It just makes it worse. I fill like I've been giving a prison sentence to stay in my own home. She has been with me right at a month right now. How do people do this on a yr to yr basis. I'm about to go nut's now. I need some info and help, for me and my fur kids. As it is depressing to me and them both, and it's alot to weed thru. Thanks everone!