Get over depression?

i'm a sophmore in high school.
I used to be popular and happy before i dated my ex who was very unsocialable and was strange.
I sacrificed a lot of my life to be with him.
Including my friends and myself.
I just can't figure out who I am anymore.
And no one really cares about me anymore because of the mistakes I made.
Recently two of my friends just passed away in a horrible car accident after coming from a church missionary.
I'm actually jealous of them because I know people miss them and think about them everyday.
But I'm still here and no one even treats me like I'm alive.
I want to overcome this and sometimes I think I do.
But then something else comes and crashes me down again.
What can I do to beat this depression ?

try thinking of good things in your life i get like that too i just feel like there is no point in living all you need is someone to talk to so find a person to talk to you and explain everything go out and find a new friend or to get everything off your chest write something in a book.

Treasure the life you have. You are alive, so treat yourself like you care.
how do you know that it is depression???? I am not trying to be mean, but you should try not to diagnose yourself. Depression often comes in many ways.If you show little interest in once-enjoyable activities, if you feel sad, helpless, tired or worthless, and if your eating and sleeping habits have changed greatly, see your doctor to determine if you have depression.
you are so young and have the rest of your life to look forward to,This is just a faze and it will pass.You will grieve for your lost friends and eventually things will improve.
Try making some friends away from your usual environment, this might help you to get your confidence back.