regretfully

adverb2

1. •
   In a regretful manner, with regret.

   • The steak and chips partaken of for lunch seemed now to belong to another decade. He regretfully recognized the fact that he would not make a success of a hunger strike. — 1922
2. •
   (nonstandard) Unfortunately, in a manner inspiring or deserving regret; used only as a sentence adverb (to introduce and modify an entire sentence).