Single mom dating help!

So I'm dating an amazing guy and he is aware I have a kid. He recently told me that his sister doesn't like the fact that he even chose to date someone with a kid. His mom also isn't too thrilled about it but she is happy as long as he's happy. I did break down yesterday because it sucks that I'm seen as a defect just because I have a child when in reality I'm such a good potential partner for him and I have my shit together. Any advice on how to handle this and the mom+sister ?