A symptom of Susan's grief is revealing itself to be anxiety.
She's afraid to do time sensitive things, so she procrastinates until they cause a problem.
She's afraid to open her e-mail even though there's nothing scary in there.
She's afraid to mail her amended tax form even though she's due some money.

Susan and anxiety go way back to when she was little. Then during both her pregnancies she had panic attacks, those things were mind blowing. A dead husband's got nothing on panic attacks.
Nothing.

The panic attacks were special, they came in the sunshine of her happy life, taught her some stuff and haven't been back since. They also changed Susan's relationship with anxiety; it's cautiously cooperative, she gets ready when she knows it's coming, and it always comes to tell her something.

Susan sees the pattern in the things she's afraid of lately.