How do you deal with your mother that was just diagnosed with dementia this past September?

She is acting like a four year old brat because she was not the center of my attention for the past two and a half weeks. I was sick still I saw her a couple of days and then I took a trip with my sister. I told her about the trip but did not remind her. I had care set up for her and my hubby, 2 grown sons and 11 yo daughter that was taking care of her in my absence. She yelled at my husband because he told her the truth he didn’t know exactly where I was. Just I was on a trip with my sister. She would not go eat with them. She would not go with them to grocery shop. If called she would hang up on them. She expects me. Me to be on call 24/7 and tell her everything I do. Not going to happen. I reminded her I’m grown. We love her. I also made sure she was taken care of. She said she didn’t care because it wasn’t me. Then she said she wanted to go to Walmart with me because I was getting my script filled. I’m sick need surgery. She doesn’t care. My sister said sure we’ll take you. So I had to take her. She was still acting like a brat. Even after I dropped her back home helped put some of the stuff up she was still acting like a brat. How do we handle this? I think she wants friends but she’s not friendly. We’ve had nice church women try but mom did the 4 yo act. This is rough.