I know what you mean. But don't let them get to you!
Dress for yourself. Dress however you feel beautiful. Let the rest of the world worry about their looks- be secure in who you are and what you look like!
As for your boyfriend- I have an idea. Look in men's catalogs, and find a picture of a man that is about the same build as he is now. tear it out, bring him the picture and say, "honey, this is how you look now- this is the size you are" I think it is always hard to see yourself in the mirror as others see you. I did this for one of my friends, and she now has the picture on her fridge... just so she knows how she looks to someone else!
Best of luck with everything- and good luck finding cute outfits!
(I find lots at Lane Bryant)
Take care,
fm