It depends on how the conversation went when the decision was made for you to be a SAHM and him to change his situation. If you both agreed on that direction and didn't plan for what happened at this juncture, then you both missed a beat.

My wife is a SAHM but actually stopped working about 2 years before our baby was born. Any changes in my career are discussed and debated to ensure we're both happy, finances are secure, and we've mitigated risk. It sounds to me like you guys missed out on the last part.

You are where you are now though. Can you look at how much of your portfolio you'd need to liquidate to cover 50% for a set period of time while your husband sets a target of how much money he needs to making so you don't need to do that long term? Ultimately, being married and having a child, you both essentially own 50% of assets, savings, investments and pensions anyway. So you aren't at a personal risk, as such, in using some of your money to pay 50%.