Grow up!
Hang on a minute mate, get a grip on reality.
You hate this guy because he thought of himself and managed to secure a job with higher prospects and more money?
Okay he may not be the best man for the job and you may feel betrayed because he went behind your back, but so what?
I feel you are directing your anger at the wrong person. How can you hate someone who is taking an opportunity to better himself?
You've already said you are the one who got all the training and the 3 months experience. Have you said this to the selection committee?
These are the people with whom you should be directing your anger. It’s up to you to present to them the case that the company has already invested time and money in you and that you are qualified for the job and you feel they have made a mistake in picking the other guy.
They will bullshit you with an excuse and that is when you should prepare your CV and get ready to walk.
And walk you must because if you stay what will happen is your mate will get the job, find out he is well out of his depth, turn to you, the man who is qualified and ask for help.
If you agree he will be getting paid whilst you will be doing the work.
And if you refuse you will get sacked for not being a team-member.
How bad will that look on your CV?
Terrible.
However, if you prepare to move jobs now you have a legitimate reason for doing so (passed over unfairly for promotion) and you have corporate training and 3 months experience to sell yourself.
Once you've gone this guy will either sink or swim but the problem won't be yours anymore as you will be off doing something else.