Should I be angry by the lack of support my wife's family is willing to contribute? [View all]

I certainly know that anger only hurts those that harbor it. I feel that being angry doesn't help any situation. However, my spouse has two siblings, both professionals, that are completely unwilling to contribute to the longterm care their elderly mother desperately needs. As retirees, we are on a fixed income and paying the entire cost of the care while we watch the siblings buy new cars, take expensive family vacations, and claim to not be able to contribute a dime to their parents healthcare. This will impact the money we have set aside for our longterm care and thus affect our kids futures. Resentful? I'm thinking I'm resentful.