Don't forget that it's okay to feel a little selfish sometimes, a little angry. It's a normal reaction to taking on such a big responsibility. My mom has stage 4 breast cancer, and she's refused traditional treatment so unless some sort of miracle pops up we're working on giving her a few good weeks. I'm her primary caretaker, and it's a lot. Sometimes I feel like it's too much, and I know you'll reach that point too. Just remember that it is OKAY to be upset. Trying to make yourself feel guilty about how you feel will only make things worse. So, acknowledge your feelings. You have a right to them.
I read a book in my back yard when my mom is sleeping - it's very relaxing and gets me 'out of the house'. When I don't feel like reading, I sit outside and give/get support on 3FC. This forum has helped me so much with the caretaker issue, it's almost been more of a help there than with the weight loss! But I know, too, that having a place to vent has helped me stay OP. I know I would have given up by now had it not been for this place. So don't forget to keep checking in, as often as you need to! We're all here for you. That's what this place is all about.
Good luck, and I hope your dad has a speedy recovery.