Can this world really be as sad as it seems?

I was a happy boy who enjoyed his life but one day I met a girl. She was perfect and I wanted to pretend being someone else to like her and we fell in love. Then I stopped talking to my friends and I forgot about school and my hobbies. She was everything for me I wasn't everything for her and she ignored me. I always waited her. I waited her call or her message. I knew it was a sad life but I am just addicted to her but then she left me. I though she liked me...

2 years with depression. No motivation. No happiness. I took antidepressants once and they made me feel the happiest boy in the world and I socialized with everyone and it wasn't hard to study but the effect of the antidepressants dissapeared after a month and now I am depressed again. Will it ever end? I am too young for being depressed.

Now I fear people and I think that they want to hurt or kill me purposly

i dont think depression is a matter of age now. i've read kids in 7th grade go in depression because they got less marks n the kids went in immense depression.

also some types of depression are hereditary.

it also depends on the environment around u. its like if u are raised in a family where the atmosphere is chilled out/relaxed n no one puts any pressure on anyone, then the kid would also have a more relaxed attitude towards life.
similarly if the house has members who are in depression then chances are the behavior pattern may get ingrained in the kid

i can speak for my depression. its not as bad as it was at one time. there are still times when i feel very low. but the coping mechanisms help me.
accepting the negative thoughts
allowing the depression to exist
not putting pressure on myself to recover in one day
eating more fruits n less spicy food or fast food
some walks in the park help