You handle it by punishing her. Does she have a phone? An iPad for entertainment? A tv in ber room?
DH needs to stop encouraging her - he needs to apologise profusely to you for joining in the 'fun' she had at your expense. It would be a very good idea for DH to apologise at the dinner table while you're all sitting there eating, and you and he can tell her off together. She needs to be cut down to size.
Would he be willing to participate in a set piece like this?
You will need to explain to him that it is never, ever ok to comment on a woman's shape or size, and it is never OK to encourage a child to believe such comment is acceptable or funny, either giving or receiving. If your H won't do a set piece apology to you, you need to address the whole family over the dinner table, and tell them what was unacceptable and why, and that you expect a sincere apology from both H and D. Then get up and leave the table and do not do a single thing for either of them until you get an apology.
For your part, you need to put an end to the wallowing and the angst. Take time to go shopping and try on clothes. Buy clothes you like. If DD pipes up with a rude comment, tell her you don't remember asking for her opinion. If she compliments you, thank her. If she or anyone else in the family speaks to you like that again, get up and leave - leave the cinema, cafe, restaurant, church, theatre, pool, zoo, whatever. Do not sit there while others insult you.
Sit down with DD and explain that roasting is separated from bullying by a very fine line and can only be done when both parties are in the mood, and fornthe record, you are not in the mood, ever. Tell her if she ever speaks to you like that again, she will be punished, and if you ever hear of her crossing the line into bullying another student, she will also be punished.