What should I do with boyfriend that is careless with my feelings.?

As a child and teen I have been super skinny, recently I have put on fifteen to twenty pounds and my boyfriend told me quote "you are the same weight as my sister and she has two kids" (I have no kids btw) I understand that I need to get back in shape but the way he said it was very insensitive. In fact it makes me want to eat more and not care what he thinks. I went to him for support and instead he ridiculed me. When I confronted him he said he did it as motivation for me and that me calling him insensitive was ridiculous. This isn't the first time he said something mean about me and when I confront him it is always the same response...that I am too sensitive and that is what he hates about me