I used to be like this, in fact years ago I used to post a lot on PC about how I was so behind from all my friends. The biggest trigger for me was Facebook and seeing everyone so happy and involved in their lives. Well I deleted Facebook and got rid of all my friends.

BY NO MEANS AM I TELLING YOU TO DO THAT!!!

I am just saying it's okay to be jealous and envious and posting and venting about it is a healthy step in the right direction. Your feelings are valid, just remember that. The absolute worst thing (someone already mentioned it) is COMPARE yourself to others. What is happy for some maybe another's misery. You will get where you want in time, and life is not all shiny and roses either. I am sure your friend has bad times she doesn't tell you about. People have a good way of masking things. Just BE YOU, and be kind to yourself everyday, that's the best thing you can do.

Hugs!!