How to stand up to my boyfriend?

My boyfriend makes me cry a lot. I'm very sensitive and he knows that. When I was pregnant I cried a lot of course, now after having the baby I have the baby blues. When he first met me I was suffering from depression and he helped me, as I got over it. Lately he started calling me a "cry baby" and I told him I wasn't and he said "well you earned that name." I was so upset I felt like crying again but I held it in. I don't like to be looked at like I'm a punk its embarrassing. He just seen this side of me more because I was depressed and I got pregnant after getting over it. I don't say anything to him when he hurts my feelings because I'm afraid of what he's going to say. Sometimes he would just look at me knows something is wrong and asked me, I would say nothing because I feel like I can't talk to him and when I get the nerve I just get choked up and just let it go.