How do I help my parents? Father in denial, mother stressed out.

My father (84) has (undiagnosed) dementia (not too bad) but won't see a doctor. My mother (87) has slight age-related cognitive impairment. Mother's stress related to dealing with my father has manifested in acute itching. She has seen her doctor and been prescribed creams but nothing is working. I told her she should tell her doctor about her problems dealing with my father, thinking he could suggest someone (therapist?) to help her deal with the stress, but it seems the only person she shares this with is me (and what do I know? this is my first time dealing with this type of problem). She is also hard of hearing (has hearing aids but not very helpful - she hears but doesn't understand the words), but so far I have not been able to get her to go to an actual hearing doctor for further diagnosis. This adds to her difficulties with my father, which is frustrating for him, creates more tension and things sometimes escalate to him yelling at her. She has finally agreed to have a caregiver come in to their home twice a week, which she likes (dad doesn't really want anything to do with the caregiver). I have suggested that she move to an assisted living facility (she is also frail and has COPD). My mother sometimes wants to do that, but doesn't think father will want to go, and if she goes alone, what will he do? I can't imaging him living alone. I don't think we could force him to go. He has always been a very difficult, stubborn, my-way-or-the-highway kind of guy. He has no friends (that I am aware of). He always eventually stops liking anybody (neighbor, doctor, plumber, etc.). So, I just don't know what to do, or how to bring the subject up with my dad, without it sounding like I'm trying to control him or making him feel like I think he's a child. Because of hearing/slow thinking problems, I think I might put my concerns in writing, so they can read it slowly, instead of trying to say it to them, with interruptions and segues. Any suggestions would be appreciated.