@rockvillemom - you asked what should you say to friends who say to you "At least you have both your parents alive:. Since they are well-meaning, and don’t understand the abuse you’ve been through, the best advice I can suggest is to tell them “Thank you, it’s kind of you to say that”, or even “Thank you, I sometimes need to hear that kindness…” and all the while, you know that they think they are being kind to you, but they are really being more kind to your parents.
I think you are on the right track, managing your father like a toddler.
Without making excuses, his behavior/tantrums are brought on by stress, and you have the beginning of the right idea by managing them with regular snack/drink. If he were in a nursing home or elder care center, he’s probably be given sedatives to prevent / control outbursts.
Somehow, despite not having great parents for role models, you have made great progress in the last year, by recognizing how his destructive behavior is unacceptable, and you have chosen to be the best person and role model for your own amazing kids and husband, but most importantly for yourself. I am sure you have read over the early parts of this thread, and I think everyone here wishes we can offer you emotional support, and empathy, because your parents never showed you any empathy ever - they are not capable of doing that. But somehow, you are incredibly supportive to them despite how hard it has been for you.
It is not easy dealing with parents who refuse to acknowledge that they are a problem. And the sporadic behavior - like the giving up the car - can sometimes be one step forward two steps back.
I suggest that you purchase a small bracelet or lanyard necklace that will hold a list of his recent meds/dosages/doctors and history. Some elderly include a rosary, or a prayer card, etc. on it, as a way to help them accept that in the event of an emergency, the relevant history is readily available.
My son recently told me that he had thought I was harsh when I would show that I was often stressed by my mother. But he house-sat for us when we went away, and he stopped to visit her. He realized that she really is hard to deal with - it can be exasperating, but after I let it out (not around her), I usually feel much better. Be glad that your children love and support you, they understand that you are trying to do the right thing. Focus on them and I hope you have a special, loving Thanksgiving.