Barbara Corcoran credits her motivation to succeed to a hurtful insult she received as a young entrepreneur from the person who knew how to hurt her the most. 

Today she's a real-estate mogul, self-made millionaire, and Shark Tank star. In her early '20s, she started a real estate firm with her boyfriend Ramone Simone. He put in $1,000 and they were business partners.

For seven years, they built the Corcoran-Simone company together. Then he came home one day and announced he was leaving her for her secretary. 

As if that wasn't painful enough, he dug the knife in deeper and told her: "You'll never succeed without me."

"An insult is advice in reverse."

Corcoran recently shared what she learned from the experience in an update on LinkedIn. She took this insult as advice -- and flipped it on its head. 

"His sage advice made me more determined to become a big success and I worked harder than ever to prove him wrong!" 

Instead of trying to ignore the pain of his hurtful comment, Corcoran used it as motivation. She would not grant him the satisfaction of his prediction coming true. 

Proving the prediction wrong

"An insult is advice in reverse," she says. "It almost always proves to be the best advice you'll ever hear."

After their joint business was dissolved, Corcoran started her own real estate firm. The rest is, literally, history. She built the business from the group up and became one of New York's most successful names in real estate. In 2001, she sold the Corcoran Group at age 51 for a reported $66 million. She had proved Simone dead wrong.