It is very hard, in the care of another person, to set aside your wants/needs/expectations/desires. Seldom is one solitary person sufficient to deal with the needs of a person with dementia and chronic illness. It can be a conscious choice that is affirmed and reaffirmed on a daily ... or even several times a day basis. But eventually, there needs to be a support system in place Gizmo.
Not just for your spouse, but also for yourself. We can do esteemable things, but we can wear out, burn out, become aggitated, and depressed. Hospice, volunteers, support groups, and supplemental care givers offset this for most families. It may be desirable for your spouse to prefer being with you exclusively... but the reality is, it is not beneficial for you as you go through this process with your husband.
I like the idea of calling in support, a housekeeper, perhaps hospice, and boundary setting with your spouse in his lucid moments. Though I know it can be hard to tell and differentiate moment to moment. You have had a lot of concern about his response to people coming into your home, though I do not recall a situation where this has occurred.
I did this just this week with a family that was so freaked out about their mother's reaction that they expected me to "be locked out of the house". Experienced people know how to deal with this. I knew how to deal with it. Hospice people know how to deal with it. Even when aggressive postures are made by the client.
Sometimes, you can't predict the response of your spouse, unless you try. Perhaps your depression and the realization that this is taking a big toll on you is the beginning of a time where you can supplement your care of your spouse with outside sources. There is no shame or blame or guilt in not being able to sholder the 24/7/365 (24 hours a day, 7 days a week, 365 days a year) care on your own. You are best served finding services that will supplement the measure of care you can comfortably carry.
Sometimes, I have to tell myself, "All I can do is the best I can do and that is the best that anyone can reasonably expect." I take the "tough ones", even in long term care, or agency. Because I am best suited to deal with them. But not all people are suited, and those with unresolved spousal issues are especially not suited. Unless very solid boundaries are in place for yourself and you are capable of disputing irrational thoughts on your own... it is a losing proposition for both you and your spouse.
It is sad. It is tough. But with foresight and planning, and the experience of others who have been in your situation, you can make the best decisions for you both moving forward.
It can happen. I know it for a fact.