regretfulness
n. 后悔,遗憾
例句
I would like to express my regretfulness and my heartfelt sorrow and loss for all the crimes committed from 1975 to 1979.
对于一切发生在1975年至1979年期间的罪行,我希望表达我的忏悔和我内心感受到的悲哀和失落。