First off, I cannot truly emphasise with what you're experiencing because I only suffered through the most minor bout of acne during my teen years *touches wood*.
A lot of people will tell you it has a lot to do with your diet, general heath et all. So, do you eat healthily? Do you exersise? In conjuction with the dedicated anti-acne remidies you could do a lot to improve your self-esteem by looking after yourself.
On a side note, are you sure the girls you described were actually laughing at you? They might have been in hysterics about something completely irrelevant to your person. That said, if they were in fact directing their laughter at you then you have the utmost right to consider them shallow ****(s).
Hope everything works out for you, and good luck
