Hi @leeandpat – I can really relate to the issues you are having. As @colleenyoung mentioned – I'm facing several of the same ones myself. I will share some of the things that have been helpful to me.
This year I joined a Caregivers Support Group at our local Council on Aging. I learned that one of the services our local hospice offers is grief counseling for caregivers. The patient does not have to be end-stage. At least here in North FL, hospice provides support for any dementia cases that are referred to them. I learned that you CANNOT do this alone. My advice would be to seek out a therapist/counselor, start looking at the care facilities in your area – even if you won't need them for awhile, and find out what hospice can do for you. All of these things brought me tremendous peace of mind.
In regard to your husband's anger issues, I know every case is different. For me, its important to remember that anger and fear are very close cousins. I find that when my husband is anxious or afraid about anything going on in our lives, he either tends to get very weepy or else have an angry outburst – but the anger is more like a child's tantrum. It's not something that causes me – or family members – to fear for my safety. Anyway, I have learned that when I have medical issues, it is VERY scary for him so it's better if I downplay them and have a friend or relative take me. If I were you, I would consider letting your husband stay with a relative while you have your knee surgery. Also, you might ask your surgeon about the possibility of going into rehab yourself for the first week or two after knee replacement so you can really concentrate on your own recovery. I had a friend who did that and she said it was the best decision she ever made!
Is there someone you could talk to -I would say outside the family – to get some constructive suggestions on your husband's anger issues as well as how you might plan and schedule your knee surgery in a way that keeps both you and your husband safe and in a good frame of mind? Maybe a counselor or therapist?