I just need to know, did she suspect her husband of having an affair?

In the book's title story, she has become a suburban housewife who suspects her husband of infidelity.

Did she suspect her husband of being involved in Emily's death?

Because you suspected your husband was having an affair with her.

Although she has no reason to suspect her husband, she might soon put some of the pieces together.

"She didn't suspect her husband of trying to do her in?"

"Do you have any reason to suspect that your husband has been seeing other women?"

SO you suspect your husband is cheating and you want to get the goods on him.

"Did she ever mention that she suspected her husband of any other crimes?"

She suspects her husband of plotting to kill his son from a previous marriage.