Your husband is really great but has a really great financial burden for his family. My husband also needs to pay the "monthly pocket money" to his parents, but his family is shared by his brothers and sister luckily. I'm still giving half of my "pocket money" to my retired parents every month while my working brother share the most. Both of our parents are quite supportive to me for being a full time mom as they don't like my baby to be taken care by maid.
Apart from giving money to parents, same as u, we need to repay the mortgage, save money for the tax (though my husband is a tax payer, I can't see how we can benefit from the gov't!!!), insurance, household misc and expenses for baby. It's really really a big burden to my husband. I regret I spent too much when I was a working lady and didn't save much money. If u wanna quit from your job, it's better for u to save some money first, at least for yourself as u may need to support your family from your wallet occasionally, just like me :-(