Pregnancy and Husband

Hi all,
I have been wanting to have a baby for the past year. My husband keeps telling me he wants a baby too, and that we can't have a baby because he's worried about my weight. He wants me to loose around 50lbs before he even considers having a child with me. 
I feel so overwhelmed and idiotically enough, I feel that he is holding this weight as blackmail over me. I don't think that he truly cares for me and has been on this mission to change me. I have been quiet long enough, I just can't take it anymore. Do you think I'm overreacting?