Dear Beth welcome to the group. I have been a member of this forum for about two years and it has really helped me. I am not clear about your full background circumstances but would offer a few words of caution.
1) Capacity, capacity where are you and more importantly what are you. It can fluctuate from day to day, three GPs could assess it and give three different answers. The world of Dementia is rarely black and white. Your mother still sounds like she has capacity, the definition of its loss is quite a high threshold, as outlined in the mental health act website.
2) Do you have LPAs in place for financial and health and welfare. If not and your mum has capacity would she agree to granting them? They will help later on with her Dementia journey. There are threads here where people give advice on how to persuade a PWD to agree to this happening eg an insurance policy just in case something goes wrong in the future. Remember we are talking with how the PWD sees the world not your good self with a logical understanding of matters.
3) Save yourself some arguments and frustrations by using white lies, agreeing with some statements which defy logic but do no harm. My mum still goes on the bus every Wednesday to the shops whilst I am at work. Reality is she has not done so for four years, mum does not know what day of the week it is, I have reduced my employment to two nights a week in a supermarket to care for her. I am home Wednesdays and we go to ASDA to do our shopping. Same with the blister pack situation. Try to avoid arguing, applying logic,etc. Make some tea, give it ten minutes then just say well finish your pills and then we can do....... depending where your mum is she may well have forgotten the prior incident completely and come to the issue a fresh more positively. Hard to believe when I first got such advice but yes it does work sometimes. Certainly reduced my stress level.
Dementia is cruel for the sufferer and their family. Do you have any siblings who can help? You have two little girls who have to be your priority. Need to get the balance right here but remember Dementia will suck the life force out of everyone involved if you do not be careful. I am a single bloke living with my mum, no other emotional or family demands. That is a lucky position at one level, but an isolated one at another.
One last suggestion. Open up a new thread. Hell you are a fully paid up member of the club so use it fully. I saw your comment and replied as I knew this thread from the past, having previously contributed. Give some more detail if you can and many other members will see the new thread. They are a gold mine of knowledge and experience. Please tap into it.
Please keep your chin up. Try to remember it is the illness causing the issues not your mum. Somewhere deep down is a lady unsure what is happening to her, knowing something is wrong, but her damaged mind reduces her insight of the situation. A frightening situation. That comment does not change the nature of events, but hopefully might change how you interpret them. That is a key moment of self knowledge. The PWD cannot change as regards their understanding of the situation, a problem which will slowly get worse. It is the loved ones around them who have to adjust, manage their expectations, etc. Hope that helps, it did for me when a certain event pushed the mist away and I started to fully appreciate what Dementia entails.