Every day for nearly two weeks, Troy Hunt, an Australian Internet security expert, has opened up his computer to find a plea for help from someone on the edge.

“I have contemplated suicide daily for the past week,” one person recently told Mr. Hunt. “My two beautiful children and my wife are keeping me alive. I am very worried that her family and others will find out, making it extremely difficult for her to stay with me.” Another wrote, “I imagine my grown kids finding out, my neighbors, friends, co-workers, and sometimes I just want to end it all before facing something like that.”

Mr. Hunt runs Have I Been Pwned?, a site that lets people determine if their data has been compromised in one of the online security breaches that have made headlines over the last few years. For the victims, most of those breaches resulted in little more than minor frustrations — changing a password, say, or getting a new credit card.

But the theft and disclosure of more than 30 million accounts from Ashley Madison, a site that advertises itself as a place for married people to discreetly set up extramarital affairs, is different. After the hacking, many victims have been plunged into the depths of despair. In addition to those contemplating suicide, dozens have told Mr. Hunt that they feared losing their jobs and families, and they expected to be humiliated among friends and co-workers.