Betrayal is the worst thing,because it don't come from your enemies it comes from your friends.When you think you know her/him so good but you actually don't know anything.Friends are supposed to make you happy, not to be reason why are you crying.And it is hard to get over that,because you trusted them you had courage to tell them anything and then they just turn their back to you like it is all your fault.But you shouldn't cry or be sad because that person doesn't deserve to make you sad.My advice is just move on,because people are like that,and life is hard but through him you will find you best friend.And never believe people in one second,because sometimes you know them for years,but all you know sometimes are lies.And the worst is you think that they care about you,but then they show who they are in reality.And once someone broke your trust it is hard to trust someone else because you think that they will hurt you,but it is like that all the time.And after that you sometimes need a lot of courage to move on and forget about all the problems.Because it is the only way.

If she left,you didn't lose your best friend,just person who you thought it was.