not her husband, but her husband's mother (mother in law)
.......wait for the context to come out if you're confused. Otherwise you get people who will blatantly spoil the story for you in order to answer your questions. ( ⩌⤚⩌)
[Tip for the future: When a decent person openly admits to commiting a crime that's unbecoming of their character it usually means they're placing the blame on their self as a form of guilt or repentance. He didn't actually kill her mother himself but is taking the fault of an outside occurrance that's related to him and taking accountability for the whole sitchiation. Psychology 101.]
Why would her husband kill her mother???