A Russian billionaire who accused Sotheby’s of teaming up with a Swiss art dealer to cheat him out of tens of millions of dollars became tearful Friday while testifying about discovering he’d been part of a con game too common in an “art market that needs to be more transparent.”

The emotional moment came as fertilizer magnate Dmitry Rybolovlev, speaking through an interpreter, completed two days of testimony in Manhattan federal court to support his lawsuit against Sotheby’s.

Once worth at least $7 billion, Rybolovlev said he trusted his dealer, Yves Bouvier.

“So when you trust people, and I’m not a person who trusts easily, but when a person is like a member of your family,” Rybolovlev said as he dropped his head briefly before wiping tears from his eyes and continuing on: “There is a point in time and that you start to completely and utterly trust a person.”

Rybolovlev is trying to hold Sotheby’s responsible for what his lawyers said was the loss of over $160 million.