Regretfully vs. Regrettable
Regretfullyadverb
In a regretful manner, with regret.
Regretfullyadverb
(proscribed) Unfortunately, in a manner inspiring or deserving regret; used only as a sentence adverb (to introduce and modify an entire sentence).
Regretfullyadverb
with regret (used in polite formulas);
Regrettableadjective
Able to be regretted, especially deserving of regret.
Regrettableadjective
deserving regret;
