regretful

Regrettable is used of something that is a cause for regret, whereas regretful describes somebody who has feelings of regret for something: These mistakes are regrettable.They felt regretful at missing the opportunity. The adverbs regrettably and regretfully are even more vulnerable to confusion, but again regrettably relates to the cause of regret and regretfully to the feeling itself: The exam results are regrettably poor.She regretfully turned down the invitation.