Talks to me like a child because I do what mother asks, not his way. My brother just moved down here and talked to my mother with his girlfriend - a CNA. Now he thinks he knows what has to be done. I've been taking care of her for a few years now and he hasn't even seen in her about 5. He feels she takes too many pills and self-medicates. I agree in part but she insisted I give her all the pills when I gave her one day's worth as an experiment. I ended up giving her all of them along with the pill box given to her yesterday and she promises she won't run out this time. My brother starts treating me like an enabler and talking down to me. I am the oldest in the family and have been with her the longest. Should I just let him go over to my mother's house, take her pills away and distribute them to her daily? I am out of answers because I know my mother will hurt herself if she takes all the pills she has before their time. She is a retired RN and started talking weird about 4 years ago (Not making sense, asking same question etc). He didn't see it. Nobody saw it except me and her nearly 88 yr old boyfriend. She will be 82 in October.
The other responsibilities you can divide, based on the amount of time you have. Try not to think of him as stepping in your territory, though I know it probably feels that way. And work with him on what he sees as a problem. From what you wrote, it does seem the medications are. All this might be a good thing.
He's concerned about his mother - he's probably not trying to make you feel bad or give you a hard time. Stand up for yourself (and your Mom) if you think he's misguided or mishandling anything, but apart from that, I'd welcome the help and the chance to divide responsibilities. Think of him as reinforcement, not competition. Nobody should have to deal with an aging or demented parent alone.
Keep the medication issue for yourself, but I would consider some other method of handling the medication, especially since in your profile you indicate she has dementia. Is she living alone?
You're also going to have to be firm with him and establish right now that he can't treat you like a child, or impose his or his GF's ways and advice, particularly since he hasn't been on the dementia journey with her as you have. There's a lot he'll have to get used to and if he's as aggressive with your mother as he is with you, there are going to be either some tears shed or some hostility, confusion and/or animosity.
So let him know where he stands right now.
He can easily help with groceries, meals, doctors appointments, etc., but i would keep him out of the medication management. He'll probably fight you - you can always play the nasty trump card and throw it in his face that he hasn't been with her on the 5 year journey AS YOU HAVE and he needs time to learn about her situation now as well as about the disease.
He'll probably say, "well, I'm here NOW!" You can response with something to the effect that you're glad, because you and your mother both need help and he has 5 years of time to make up for.
Don't let him intimidate you and don't be afraid to stand up to him and put him in his place. I speak from experience.
Why not try to work as a team with your brother and his girlfriend. Make a list of what needs to be done on a daily basis for your Mom, and decide who would be the best candidate to do each and every chore. If your brother wants to take over with the dispensing of the pills, let him.