where to start

My dad has a terminal brain tumor and we are in our 5th year of dementia symptoms(in addition to others) somewhere between Alz and Lewy Body. My mother is terminal ill also with heart and a number of other issues. She takes the brunt of the 24 hr care with him. I am there 2x a day or more if needed and all or part of nights. I always expected my dad to die first(his last live to date was Feb 2009) so I didn't start my homework but it looks like I need to call hospice for mom and holy cow what are we going to do with my dad??? I own my own business but I cannot bewith him 24hrs. He never admits to the dementiawon't allow us to tells friends or distant family even that he is ill, doesn't see a Dr except when I double appts with mom, we do all things together- he has not given up writing checks even though most of the time he doesn't know why he is writing them. They do not drive and I am POA, MI med advocate, SS reponsible payee and Executor of the trust. So where do I start? This is all going to be so so messy and awful he already has paranoia and trust issues. Do I take him to the Dr for an evalu? and then decide about home care or assisted living home? Is it possible I may have to go to court? He cannot be alone all day, he cannot function(as much as he fakes it) through all his day to day. It takes us 2 hours to get him dressed. Should I decide now on a facility? It is so important to respect and honor them but I also need to protect them. Yikes I feel lost.