People like to make themselves feel better by putting others down or belittling their accomplishments. Maybe those jerks are having trouble in their own lives and are feeling insecure, and see the easiest way to bring themselves up by bringing you down. It sucks, but there it is. You can ignore them until they get the message and shut up, or you can tell them right out that what they're doing is not cool.
In the meantime, try not to take their comments personally, and remember that they are being petty and small (and not in the way that we all want to be small! lol
), most likely making up for some lack in their own self esteem. People who are rooting for you and actually care about you will be supportive and remind you that you should be VERY proud of yourself for the progress you are making. Like us!