In English, these two phrases which are almost the same have very
different meanings. If you say "I f*cked up", that means I messed up, its like an apology,
it's acknowledging you did something wrong. "I f*cked up" or "I f*cked that up" or
"I completely f*cked it up." But if you say, "I'm f*cked up"
and instead of I you say I'm, then you're saying I'm really drunk or I'm really high on drugs.
I'm so f*cked up. Two very similar
phrases but very different meanings. Quick add-in, if you don't want to cuss,
you can say "F'D up". "I really F'D up, I'm so sorry." or "Woow! Last night I was really F'D up."