monica, The standard version is "I am terribly sorry." " I am terrible sorry" is used conversationally by certain segments of the population in the U.S. Other variants: I am dreadful sorry. I am awful sorry. I am frightful sorry. 'Terrible' is considered a quasi-adverb, i.e., it can be used as an adverb while properly speaking it is not. "Terrible".....to an extreme degree, terribly. Webster's 3rd Int. "Terrible"......terribly Oxford 2nd ed.

I am terribly sorry is the correct phrasing. It is not correct grammar to have a sentence with "sorry" hanging out at the end. This sentence would sound very awkward at the very least.

"terribly".

The answer is, I'm terribly sorry. But you can also say "I am terrible, sorry" which means that your very bad at whatever it is your doing. If your emphasizing the "sorry" then you need to say I'm terribly sorry. Hope this helps

I believe that either "I am terribly sorry." or "I am terrible, sorry." :)