How will I decide when it's time to move from home care to nursing home?

I don't know what you are dealing with but there are a lot of steps available between home and a NH, would senior living or assisted living be a better fit?

Getting you added help to care for him might work and allow you your independence still.

Just a thought.

That you are asking, it is a good signal that you recognize that you are nearly there if you aren't already. And that is ok.