My guess is he had that conversation knowing you were listening because he thought he could use it as leverage later to try and guilt you into helping.

Everything you said was 100% correct. His father is a grown man who can get a job and work for his money like everyone else. Likewise, your husband can get a second job and work to pay for his father is he wants more money.

This is however, a HUGE red flag.

He wants your money, and he feels entitled to it.

Make sure there is NO WAY for him to have any access to your money or the money you are giving your family.

Lock everything down, make a separate bank account if you have to, and hide your debit cards and any checks the bank might have given you when you opened your account that might be laying around.

I hear so many stories on here about people in similar situations waking up and finding huge chunks of their money gone, accounts drained, or family in tears because someone drove over and guilt tripped them into giving them the money back.

Let your family know what is going on so he can't trick them.

This might seem like overkill, but you can go back in time to make money that is gone come back.

NTA, keep helping your family and think hard about if you want a relationship with someone who values your sisters life, your families struggle, and the hard work you do so little.