Judging me after child birth.

Before I got pregnant I use to have a nice body shape as I was constantly at the gym. After I have birth I gained a lot of weight, stretch marks, my buttocks shaped changed. My fiance is constantly telling me I have an old lady's body when joking around. I have talked to him and told him it bothers me and he denies it being true. However when we argue he is constantly reminding me how my body changed, how my stomach got wrinkly, and how my butts shape has changed. I don't know what else to do. I told him it bothers me yet he still does it.