Sounds to me like the best way to boost your confidence is to rid yourself of the people that are bringing you down. You are well on your way by getting rid of this guy, so cheers for you!
I might be wrong, but what I am hearing is that you are self-conscious regarding your appearance. Welcome to America. Women are captured at birth by the mass media. They are conditioned from the time they are old enough to listen that they are not tall enough, thin enough or pretty enough. Billions of dollars are year is spent telling them they will be prettier, happier, more successful if they would only buy this and own that. These companies don't want you to feel better about yourself, they want you to buy their stuff in order to feel better!
Every guy in here will agree that he HOTTEST women on the planet are those that are comfortable in their own skin. I have seen 200 lb. women that I find more attactive than the waif at the mall that slouches and hids behind her bangs. You will not achieve a healthy body image by poisoning yourself with Vogue and Cosmo.
The best thing you can do to boost your confidence is to take the following steps immediately:
1) Program your TV with the V chip-thingie so that you can't watch E!, Style Network, MTV, VH1, etc. Paris Hilton will get along without you, somehow. While you are at it, just cut the cord off your TV and read a nice novel or go outside and play.
2) Program your computer so you can not see the webpages E!Online, Style Network, etc.
3) Throw away every fashion magazine you own.
4) Stand up straight.
5) Pull your hair back away from your face.
6) Smile, even when you don't feel like it.