The main reason he feels that he can speak to you in that disgusting way and get away with it is because he has somehow manipulated you into a situation where you are completely and utterly dependent on him, not just financially but it sounds like also emotionally.
Plenty of fat women myself included and plenty that I know, have boyfriends and husbands and Lovers etc. You don't need a man to survive, plenty of Us manage with out them, but even if you want a man in your life it is not true to say that nobody will ever want you because you are 17 stone.
He is using this as a stick to beat you with because he knows that he can. Believe me if you had a well-paying job and plenty of confidence, even if you were still 22 stone, he would not dare to speak to you like this because he knows that you would have the power and independence to walk out and leave his sorry ass.
It's about time you started sticking up for yourself. You have actually lost five stone and he has gained five stone. Why are you not sticking up for yourself and when he tries that shaming you you should stare him straight in the face and say well you've put on five stone too so you have nothing to say to me, why don't you sort yourself out man and stop picking on me.
I think you have been an absolute fool to have allowed yourself to become isolated away from everybody who could help you, and completely dependent financially and emotionally on an abusive man, however there is nothing we can do about the past.
The future however is entirely in your hands. Do you really want to go on living like this and have your children think that it's okay for a husband to speak to his wife the mother of his children in that fashion? Because he isn't going to stop; he will beat you down to the ground emotionally until there is nothing left of you.
No matter how hard it is, no matter how scared you are, you have to leave, and you have to leave now. You will have to go to your parents 100 miles away, because you have to save yourself and save your children from being abused mentally, emotionally, financially.
It doesn't matter how hard it is to be honest you need to save your self and your children.
You have got to get away from him because he isn't just going to wake up tomorrow being completely different person, a loving, devoted, decent man, if you expect that then you're expecting a miracle and miracles don't happen.
You're in charge of your life , you and you alone, and you must leave now while you still got enough of your self left to do it.
I wish you the best of luck for stop