I felt guilty --able to help my brother at the moment when h

A
feel/be guilty of doing sth 对某事感到愧疚/内疚,例如：
If you feel guilty of overeating, now, it is time for you to make a change.
如果暴食使你感到内疚,现在,是时候为你作出改变.

I felt guilty of not being able to help my brother at the moment when he was out of work.
当我弟弟失去工作时,我对于不能帮助他的事而感到愧疚.