contrite
"I'm afraid I was a little bit bossy in those days," she admitted contritely.
She smiled sweetly at Sean, then said contritely, "I'm so very sorry for anything I've said that has annoyed you".
It is easy, sitting next to him as he speaks softly and contritely, to forget how feared he was.

SMART Vocabulary: related words and phrases

Sadness and regret
aw
be/weigh on your conscienceidiom
bitter
black dog
breastbeating
cry
feel badidiom
gloominess
glumness
groan
guilt
guilt complex
melancholia
prick someone's conscienceidiom
regretful
regretfully
remorse
remorseful
repentant
wretchedness