I'm in the same boat, except my Dad's actually really nice - he has mixed dementia, prostate cancer, and is now bedbound after having his lower left leg amputated a couple of months ago. I am the live in carer, despite having a husband - who lives in Ireland (with our dogs and cats), as do I 'officially' - there's no one else to do it, so I'm also housebound now, 'cos he can't be left alone. Might get a couple of hours a week respite in the New Year, if I'm lucky!
I too shall be producing a full dinner on the day, and he is bound to proclaim the meat 'tough' and himself full after a few nibbles. Luckily, I have a friend and her Mum coming for Boxing day lunch, so there is something to look forward to :)
Personally, I intend to self medicate with wine and cocktails, eat my favourite food, stick a DVD on for Dad (have got him a couple for Xmas presents), then come and watch stuff I like on the computer. I'll have a chat with my husband via FB Messenger (he'll be alone on the day), I'll Mumsnet, and the time will pass. I'll probably end up putting carols on and having a bit of a cry after the wine does its thing, and then an early night.
Being housebound means I can largely ignore the trappings of the season - but gawd, am I bored! If you're around on the day and fancy a chat, feel free to PM me, we could attempt to keep each other sane :)