Not sure how to cope with someone i know and love that is doing this for his family and it is alot of responsibility financially and time consuming. Not sure if I will ever be as important to him as they are! He is a wonderful loving man with a long list of priorities! He works very hard too. The dynamic is large!
Caregiving has its difficulties. My wife and I know we'll how caregiving can be draining on us at times. We have a daughter in wheelchair and caring for both my aging parents. Well now one is in a nursing home, but there has still been a lot to do for them there yet. We've needed each other to get through this last 4 years!
So if you really love him deeply, open up to him and have a good talk. See where it goes from there.
See if you can get him to realize that the demands are excessive. If he can't accept that and make changes, don't let yourself get dragged down too.
Take Fawnby's advice below.
If he's giving you vibes that they are the most important people in the world to him, run, don't walk, to the nearest exit.