My nan has dementia so no experience of a parent but have witnessed the effects it has on a family.
My nan has Vascular dementia which I think is mini strokes on the brain which gradually makes her worse and worse. She is now doubly incontinent, unable to speak and fading away before our eyes, my grandad doesn't want to put her into a home. The saddest thing for me other than watching my grandad go through this is that she isn't my nan any more but she hasn't died so haven't had a grieving process to follow, she just has a vacant look in her eyes.
As a family we laugh and joke about most things so generally try to put a face on a laugh when she does random things like hiding false teeth, pooing in the garden, falling head over heels into the pond and looking likr the creature from the deep but it is hard.
My nan goes to day care 3 times a week, and into respite now 2 weeks on 6 weeks off which has helped to release some of the pressure for my grandad but he feels so guilty even for that. He goes to a dementia club for carers and gets support from others going through the same, My mum and Aunt help out when they can and I try but with 2 kids its difficult to take on much.
Contact your GP amd local council for advice on respite, care at home etc for when times get harder, in the very early stages your dad may be able to get medication to slow the process. also check out sites for dementia they will have lots of advice on how to cope.
If there is anything specific you wand help with let me know and I will ask my mum
Sorry to hear you are going through this. You might want to think about telling people so they can support you and your family, it is hard fo you though as it is quite alien to alot of people and they don't know how to deal with it so sometimes shut off xx