Private schools are alot more intimate and respectful ..they dont insult the intelligence of the students ....they allow more freedom of choices and as FB2190 says its smaller so your get to know people better and the teachers ahve more time with the student, aslo its more of an adult environment ....i did a little work at a private school and noticed how the kids actually talk to the teacher as freely as you would to a best friend or a family member, i was a little shocked comparing it too public schools, i suppose it breeds anti social behaviour(bullying) from other students and the classes are over loaded, the teaching is either too strict or too lazy and if your showing signs of indipendance or question the teacher in the form of debate your being "naughty" .....
anyway back on topic i also had a down time at high school, i remember being picked on non stop, i ended up skipping many classes for the soul reason that i knew i would be targeted because i was a bit shy.
it gets alot easier to know people once your out of the (PUBLIC SCHOOL) environment.
you could consider attending a TAFE course where the system works in your favour, you can be feeling down and still enjoy the environment at insitutions like that, or a private college if you can afford it.
i hope you feel better soon, you deserve more then that