When National Football League owners adopted a new domestic violence policy Wednesday, in a way, it wasn’t just for the wives of football players. It was for Susan Williams, too.

At first blush, Ms. Williams is only tenuously related to the NFL scandal that spawned the changes. She left an abusive relationship more than two decades ago, long before the video of Baltimore Ravens running back Ray Rice knocking out his then-girlfriend, Janay, turned a spotlight on domestic abuse.

But even for her, what the NFL has done matters. For 20 years, she has blamed herself for the death of a police officer who was killed by her ex-husband and their then-teenage son. She has blamed herself for her failure to rescue her son from the influence of a father who stockpiled weapons in the house as an anti-government survivalist.