Ryan has asked me to help you with your question.
Marriage is about sharing, but sometimes things happen and they aren't able to be dealt with in a "normal" way. The relationship he has with his dad is a lifetime relationship, there's possibly feelings and emotions connected to his dad, that he's never shared with anyone, if he even knew how to. He's already lost his mother and probably has very mixed emotions about his dads illness, maybe feeling helpless about not being able to be more of a help to his father. On top of that, to put a burden on you and have you sitting with is father? That's the way he's probably seeing it.
Money problems can make anyone mad, but add all of the other stressors, and you can see why he's so angry. Take a step back for a while. Don't insist on helping him, instead, try to make things a little calmer around the house. When he comes in have some candles lit, some incense if you like, soft music, dinner, a bath maybe. Try to do things that will help ease his tension (if you feel inclined to do them) rub his shoulders, give him a hand massage if he'll let you, after a few days he may be more willing to open up to you and maybe talk more about how he feels.
You can't "force" him to go to therapy or counseling, but he won't be able to go on much longer like this either. I say give it a little more time, don't push yourself on him, don't insist on talking about the problems right now, just give him a little space and see how that works. Best wishes.