regretful
adjective
UK/rɪˈɡret.fᵊl/
US/rɪˈɡret.fᵊl/
Definitions of regretful adjective
Feeling or showing sadness, disappointment, or remorse over something that has happened or been done.
She felt regretful about her dishonesty.
He was regretful for not seizing the opportunity.
The letter had a regretful tone.