Husband wants another child. I feel done. *vent*

So I'm a first time mom and my husband and I have a beautiful four week old baby boy. I am beyond in love with our son but I won't lie I'm exhausted. From the moment I saw two lines on that pregnancy test my life has changed significantly and his is practically the same. I carried our son in my body. I saved for maternity leave. I had the baby. I'm now on maternity leave. I still cook dinner, clean house, and provide 99% of the care for our son since I am currently on maternity leave. My husbands life has barely changed. He still comes home to a clean house, cooked meals, hits the gum and does one diaper change/feeding and then it's time for bed. I know my husband wants a second child but I can't imagine doing this again. I'm happy loving one child for the rest of my life.