alright, man. No worries, I've been there before. And I have a horrible temper, so that never made it any better. lol.
I'm not familiar with your training techniques or whatever, but I often fight lvl 9's as practice, along with occasionally facing my brother in a few sets at a time.
When I'm doing bad, it's usually because I'm either having a bad day (or WEEK, for that matter) or I 'm really rusty. (I get rusty if I don't play for a week or two.)
My advise is to calm down, compose yourself, and switch it up a bit. Maybe facing a little lower level of CPU for the day (for example, instead of lvl 9's, try 8 or even 7). Also, fight against characters that you understand more deeply; or rather, characters that you have alot of experience against. Another method I've found that helps me to improve is to browse the Internet, specifically here at SmashBoards, or over at YouTube. Watch vids of people that are famous for playing your character good, and study their play styles. Develop little tricks they use to make your game more solid.
Anyway, hope that helped.