Remember that you haven't always felt this way.
You will not always feel this way.
Right now, you feel this way. Sad. Lonely. Scared. Tired.
And that's OK. You are allowed to cry and scream and all that jazz.
Doesn't mean you're not happy about your promotion, doesn't mean you're not happy for your friend and the new baby -- it just means you are feeling sad for yourself, your dreams, your broken relationship. Right now. So allow yourself that. You can have more than one feeling at the same time, right?
And then pat yourself on the back hard enough that you sit up and take notice, and give yourself an "attagirl" for still standing and moving ahead with your life without the A. Because you can and you will.