Possible adding your husband's name to the title?

This would be the best option. 

It is your husband's issue as well. He probably always tell his parents how well he does overseas etc.

He needs to learn to tell the difficult part of his life. You guys have kids? How much it cost to raise kids etc etc.

You can't blame his parents. He sets this foundation. If his parents knows about your income. You need to tell them the big chunk of income tax and expenses etc.