I want another baby but I’m scared...

I have 3 children.... ages 18,16,10 all girls . My husband wants a son but I’m 38 now and I a little afraid to start all over again. I just started a new job and he really wants another baby. I feel like we might be to old at this point. I love children but I raised the other children practically by myself because he was always at work. Now idk if I have the patience or strength to do it all over again. He keeps telling me that he’s not the same selfish man that he used to be and he will be here to help but I’m afraid I will end up doing it alone, again.. need some advice please.. thanks