I know it's hard to live without someone you thought you would never have to; I know it's hard to live with the fact that no matter how much you both loved each other it did end. I know you miss them so much, that your body aches and you want to throw up. I know it hurts.
But you can't live your life focusing on who left and why.
Someone someday will love, admire, and accept you with all your flaws. Focus on the ones who stay, focus on how much they are under-appreciated.
Tell them how much they mean to you, remind them how valuable you are to them. Focus on the ones who share a pure connection with you, that one connection that you don't have with anyone else not even with the one who left you. Tell them you love them before it's late.
You know you are surrounded by humans who love you and want you in their life no matter what - your family, your friends, your loved ones.
Do not lose what you have, in chasing what you already lost.
You will miss so many things if you let your past become your present. You will miss those who genuinely cherish and care for you.
Do not close yourself to future potential. Restore your life with somebody who won't ever let you go.