regretfully

/R IH0 G R EH1 T F AH0 L IY0/
adverb
  1. 1

    In a regretful manner, with regret.

  2. 2

    Unfortunately, in a manner inspiring or deserving regret; used only as a sentence adverb (to introduce and modify an entire sentence).

Source: https://en.wiktionary.org/wiki/regretfully