What a blow purple. I have lots of empathy with how you might feel. Negative feedback is a complete body blow to me, it is both mental and physical. It must have been a difficult meeting for you. Bless you for thinking about the feedback giver and his journey!
Firstly, I have to say you are very brave inviting (think you asked) for feedback. Many, many, many (inc me!) others would shy away from that.
Secondly, whatever the feedback you did keep the job, so you couldn't have been that bad.
Thirdly, it sounds from your previous posts that your boss thinks you can do the new role. It would be more challenging if you weren't good at your job but great in the interview IYSWIM.
Hopefully tomorrow you can take a more balanced view (if it is ok to assume tonight you aren't feeling balanced) and focus on what you can change/need to do.
As fighting says there sounds like there is some element of gaming playing you might need to get involved in too.
It is interesting what you say about treating the interviewers like idiots. I have just received my 2nd lot of feedback from a potential client saying they don't understand what I'd deliver in my proposal.
I wonder if there is some element of me (and maybe you) not wanting to 'push' myself forward, which therefore leaves my potential client (and those that are interviewing you) a bit unclear as to what you are capable of? Esp if you are being interviewed somewhere they should know what you do, it is easy to assume they know x and y etc.
Is there someone in RL that can help you read through your application etc? I find it difficult to ask and accept help (guess I don't feel worthy) but it might help you feel more positive about this?
Try to see this as a positive, you are now better informed than before the meeting. And I'd echo fightings point, this is an important and big thing for you, but there will be other things if it doesn't work out. It will be ok, as generally things are.....Big un-mnettey hugs. 
fighting great you had a lovely day with DC1. I'd try to forget about the money, some things are priceless (as Mastercard would say!). Have you got all the stuff for school?
I was pleased that I called DH on some behaviour yesterday. He is generally very lovely, but instead of just stewing on it, I talked to him about it. Another step forward.
Staying with family at the mo. Have been happy with my approach to food. I chose to have porridge this am, which always sets me up better than the white bread or corn cereal on offer. It reminds me that I need to make the effort to do positive things like that, as in turn it encourages me to be kind to myself. One 'bad' act encourages me to think negatively and to not be kind etc.
Hope you have good Sunday & Mondays.