Why am I so mean???????????

okay...Im 15 ,btw

It started at the beginning of 9th grade..

Suddenly I had so many friends because my actual friends knew more people and we became a huge clique ...

I never bring food to school because if i did my bag would smell like food ...so as my friends were sitting there with their food and i had nothing to eat they offered me something...i said yes

but not just one time! they offered me something everyday and after some time they got annoyed ...and I even sang songs to them so they would give me some of their food...

I shouldnt have done that because it was so nice from them that they even cared about me...

I am not thankful at all!

Another example:

Last year a girl at my school died..i did not know her

everyone was sad and cried about it...everyone but me...i even made fun of her and asked myself if her death was painful...while LAUGHING!

I know..im a terrible person!

Soo...my friends were mad at me...

I also was mean to my mom..

Like already mentioned it started at the beginning of 9th grade...well that was the time i got another close friend...her name was Aileen and she was a japan/anime-freak with emo-style..

So after a time of thinking about what happened to me...

i came to the conclusion that it was her fault...silly me ...

I stopped hanging around with her and the rest of my friends because i thought it was being her

who made me become mean...

now my friends only talk to me when i sit next to them in class

and people make fun of me because i thought someone controls my brain and makes me become mean!

i feel lonely because my so-called ''friends'' are no longer my friends...

Now they are...''people who talk to me''

And the worst thing is I am mean and have no idea how to change...it really feels like i cant control it

any advice?

I want to say that i live in germany and they have another school system...and forgive me my bad english...