Dear Peter,
Without knowing more about you,it's hard for me to give you some good advice.
But firstly.I am sure that you are 1 .You said that nobody would care if you left home.What about your2 ? And other family members ?It seems that you are very 3 . You'd better go to a doctor or talk 4 your parents.They will be able to help you.
Secondly,I'm sure there's someone else in your class who feels lonely, 5 . You never know 6other people feel.Try to make friends with your classmates.And you could 7 a club to meet new people and make friends,too.
You 8 find happiness in yourself.So my 9advice is to write a list of all the good things about yourself,learn to like yourself,and then 10 will see your confidence(信心)and like you,too.
Yours,
Lily