SO nervous

my fiancé is starting to show obvious signs of pre baby jitters. I'm just over 33 weeks and we got into a discussion/debate about raising kids. My first born isnt biologically his but he took him in as his own awhile back and we are a family together with one new one on the way. He got upset when him and my son bickered because he jokingly told our boy if he didn't move his little science experiment (for fun) off of the toilet seat he was going to pee on it.  He went in to use the bathroom and my sons stuff was everywhere (he's almost ten). He jokes like this at times and my son freaked out got dramatic and ran into the bathroom almost crying before even getting there and whining to find he was joking and it had already been moved. My fiancé giggled and my son got a half anger streak and half pushed him on the side as he walked away. He told him he was joking and not to push. Naturally I couldn't help but say to both of them to be nice and that our kid just was afraid his stuff would get ruined. He proceeded to then begin a discussion about discipline and calmly stated that I had to admit since he came into my sons life my son has a little bit of a better behavior. He wanted me to acknowledge the positive impact he's had. I've always done by best with my son and I've always tried to be strict in ways with him. But yes it has seemed more affective with a male figure around backing me up. I'm not afraid to acknowledge that. Then he proceeded to admit every day he thinks about and has already accepted the fact that he believes when the baby comes he will be doing everything himself. I was offended by this actually because I single handedly raised my first son and have more experience and am more then ready to do a lot with the new one. In fact I thought it would bring him comfort knowing Id be doing a lot of the baby stuff. Instead am floored that he somehow believes that aside from breast feeding that he will end up doing everything else because he said he already does everything now. I'm in bed rest by the way. He's the only one working right now. I try to keep the house clean and cook etc but he has had to help a lot more as of late. Somehow that made him believe he does everything and is now believing he will be doing everything still when the baby is here. I tried my best to defend myself. Listing what I try to do now and why it's harder for me right now ... Listing everything I did with my first born but he would then say I had my parents help. Which is and isn't true. I lived there but I did everything with my son by myself. After a c section at 18 I did everything like I should. And he practically shook his head as if saying yea right they helped you. I got so mad... Like he won't give me credit for  anything and has his mind made up that it's all going to be on him.  I know it's probably nerves. Mixed with the extra strain me being in bed rest has taken on him lately. He stayed calm through everything he said. But I felt so angry and resentful for not being recognized in any way... Instead him giving himself all the credit or maybe throwing a pitty party in his nervousness with the baby approaching. I tell him not to do so much but he always calmly insists and yet I have to hear things like this later on? I just feel angry and upset and tired and not appreciated. It's like I have to do even more just to find a way to reassure him yet what more could I possibly do?