Husband has "gone dark." Help!

An Adult Day Care Center would be great for him as they give their attendees lots of stimulation throughout the day, along with breakfast, lunch and a snack. Your husband could go for 5 days a week, 8 hours a day. They are a Godsend for so many loved ones who just need a break and can rest in the knowledge that their loved one is well taken care of, so please don't rule that out despite what your husband may think about it.
He will get much more stimulation from an Adult Day Care Center than he will in an assisted living facility that's for sure.
It sounds like his dementia and Parkinson's has made this issue much worse for him and you, and for that I am sorry. But yet you say that he is "happy and comfortable" at your house, while you are not. Therein lies the dilemma huh?
Until you get things figured out for you both, please continue to do things that bring you joy. And if the day care is for sure completely out, then perhaps you may want to look into hiring some outside help to come in to be with him, so you can stay away as long as possible to be around people who lift you up instead of dragging you down.
I wish you the very best in getting this all figured out.

I can understand why you'd be hurt and angry if your husband is silent with you. That's got to be horrible. Have you asked him what's going on? Probably. Maybe ask him outright, or better yet, tell him that you can see he is unhappy and think he'd be much happier somewhere else. Tell him it's OK and don't act mad about it, but understanding and calm. Tell him you think AL would be a good fit for him because they do X, Y, Z for you and there are people and activities.

If he won't leave, your only option if you are very unhappy is to move out yourself. And hire help to come in and do what needs to be done for him.

Good luck.

If he won't agree to a day program, will he agree to AL in a pleasant facility? It doesn't seem like it. Time to get his doctor on board to recommend it. "Doing that to him" means what, exactly? How is it good for him to be in a dark house (or if he's not mentally and emotionally there, does he even notice this?). I'm not sure that he's all that happy and comfortable at home, based on your description of him. There's a lot to think about here, but it's great that you are taking care of yourself and I hope you can continue doing so. Your best chance of that seems to be getting him out of the house and living somewhere more suited to his needs. Find a good place for him and help him to get there.

There could be so many reasons, including the facts that he's overwhelmed, confused, uncertain about life, and just doesn't want to discuss his condition.

Have you contacted a Parkinson's support group? Sometimes you can learn more about a situation from those who are experienced than searching online.