Dad needs care too, though.

Hey y'all!
So my Dad is 82 and in relatively good health. My Mom is 80 and is in late state Alz. ( I think.)
Her symptoms are a little different than some, in that she is unable to really hear…she can't see well…thank goodness, her attitude is usually upbeat and positive. However, she doesn't talk much now and when she does, it's all mostly "nonsense." She will, thankfully, still get up and down/walk/uses the bathroom, but you have to sit her on the toilet. She cannot wipe herself or shower on her own. She can't feed herself etc.
The point is, my Dad cares for my Mom 24/7. He literally gets up with her at night 3-4 times, taking her to the bathroom and back to bed etc. He cooks her breakfast, gives her her medicine, feeds her, bathes her etc. EVERYTHING.
My brother and I help as much as we can, but Dad usually just does it himself, even if we offer to help. We do take turns cooking and feeding her meals and we try to stay with her every now and again, to allow him time to leave the house and have a break, however, I know it's not nearly enough. He is alone with her pretty much all the time. I work almost an hour away and I have 3 older kids of my own. Dad hates the idea of a nursing home and I totally understand that, especially when he is relatively his "normal" self, but Mom is not.
Dad can still drive and does yard work etc. That sort of thing. However, he is still 82 and recently, his younger brother passed unexpectedly. His brother was his best friend. That absolutely broke his heart and he was (and IS) grieving that while still taking care of Mom 24/7. Dad says that money wise, we just can't do a nursing home yet. Same with hiring someone to sit at the house. I know he would NEVER leave his home to move into Assisted Living with Mom. I feel like it would crush his spirit. I guess my question is, how on earth can we help my Dad and give him breaks that he needs, when it's physically impossible for us to be there all the time or even as much as we would want, due to our own schedules with work/responsibilities and my kids etc. (I"m divorced, so no extra help here either.)
I worry that Dad is going to injure himself or overdo it and I know he just loves Mama and is trying so hard to keep her at home, because she does seem to know she's "home". UGH.
What are some other ways to offer help and relieve him of some of this?
Any other ideas?
Like I said ,his brother was his best friend and now, he is gone.
Most of their other friends are in their 80's too and are fighting their own battles.
My brother and I are there all the time and my kids come to see them too, but I know it's not the same as having friends and being able to just come and go as you need to etc.
My parents have been married over 57 years now. I appreciate so much how he cares for Mama. However, how can I help?
I do cook now and then…we take turns feeding Mom…I run errands/groceries for him…I clean the house etc.
But I know Dad is lonely and he's heartbroken seeing Mom like this.
She's not able to relive good memories with him or even hold a conversation.
SIGH.
What a horrible disease.
Thank you for listening and I'm open for any ideas.

XOXO Love to you all.