No I'm not. Well, actually, yes I am.
"I'm sorry" is a phrase you use in English for apologizing. Unless you don't mean it - then it's just one empty contraction and one empty five-letter word.
But I really am sorry. Read my contrition.
An alternate use, in a different context, is an abbreviation of sorts for "I'm a sorry ass", which, while true here, is not what I'm aiming at. This is just a garden-variety apology.
Also a hit song by 1950s singing prodigy Brenda Lee.