Hi Sara and welcome to Talking Point (TP).
Here is a link to info on what's called Compassionate Communication that may help you when dealing with your Dad's confusion in conversations.
https://forum.alzheimers.org.uk/sho...ionate-Communication-with-the-Memory-Impaired
It will probably also help your Mum to have a read of it.
Ironically, it's probably your Mum who needs your support right now rather than your Dad!
There are many practical things that will need to be taken care of such as applying for Attendance Allowance, sorting Power of Attorney, getting their finances in order etc and which your mum will no doubt welcome getting some help. Also things like preparing their home with any future-proofing adaptations, even if not needed yet.
Encourage your Mum to keep up with her own activities and life. It might be that will entail your Dad going to a day care centre or having a sitter or befriender come to the house so that your Mum can get out. The Alzheimer's Society is a great source of info and advice.
Sorry - my reply is a bit rushed but I'm sure you'll get lots of other advice soon. Keep posting and asking away!