Most Helpful Guy
Unfortunately... welcome to the jungle. Shitty, unfair things happen, and push comes to shove, people look out for themselves first.
Your friend doesn't give a shit because she is going to be happy out of the situation... did you think she'd give him up for you? Not happening.
You simply have to accept this, learn from it, and move on. I wish I could sugarcoat it for you, but you simply have to grow up and move past your insecurities. You need to determine what it is you want in life, break down the steps to getting it, and do it.
Depression is due to dwelling in the past. Close those chapters. When thoughts of the past surface, push them out and focus on your goals for the future. Drown out negative emotions with positive actions that achieve your goals.
It will help to cut both of those people out of your life. That should be step one. Get rid of anything that holds you back.
Most Helpful Girl
Don't be embarrassed at all, it's okay. That's really crappy of your friend to get with him like that. I am so sorry this happened to you. I don't really have any good advice, except to say that time heals everything and all you can do is look ahead and try to focus on other things. Depression sucks, but things will get better.