If that does happen, it's possible to resolve your anger without them; but if you have a therapist to explore that anger, you also have a good chance to work it out with your dad while he's alive. I know that someone in their 60's sounds ancient, but it's far from his final years, unless your dad has some medical condition or dementia.

I don't have a physical disability and my situation is not at all like yours, but my dad died when I was 16 and my mom now has dementia. There is no working out my anger with them, but resolving all that emotion is pretty much an inside job when it comes down to it anyway.