When you're very, very close to people, you tend to feel what they feel. For example, if somebody makes a joke about your husband's big nose—which is big, but in a distinguished way that was handed down from his grandfather—you may want to also punch that person in their cute snub schnoz. But where your empathy can occasionally go wrong is when your husband's business fails or your teenager goes into rehab or your mom admits she's a shoplifter. All of a sudden, some confused calculations take over your brain, like: the failure of someone you love = the failure of you or your family or your life.
Doing this once—taking a deep dive into panic and depression—leaves you with an understanding that can change the course of your life: You did not steal a dress from Saks or take heroin. You're fine. And you need to keep on being fine in order to help those people you love get back to being fine with you.