all Im gonna say, is it might sound harsh, but your not being strong. You are saying all the things he'll do if you leave, and all the things he'll do if you stay. When it comes down to it, you have to make a decision, he can only say, given the circumstances what we think you should do, you have to decide. Maybe he won't pay child support if you leave, but you do kknow there is such thing as court, and do you really think he'll do that, or was he just saying it out of anger, if you think he's serious you should know the answer already. You are in a tough circumstance, but I am glad you are not in a abusive relationship. I know you may not think i know because Im 17, but like many people i have been in scary relationships, and i had to figure them out on my own. -Which I thinkk is the best, really.
It shouldnt matter if you put on weight, or if you dont look 20 anymore(in my opinion) he should love you for who you are..(corny i know)