Can a marriage survive when one person doesn't want to commit?

Your husband is a bigger problem than the stepson. It's your husband who should require his son to be respectful and helpful around the house. Once you have this baby, you should not be having to pick up after your husband's grown son. You need to talk to your husband. He needs to get this straightened out for you. If he won't, you'll have to consider your options. Good luck.