Prosecutors say Disalvo and his wife Rosie divorced in 2007 after a 10-year marriage and then remarried in 2008. During their time apart, Rosie Disalvo dated Jorge Diaz. Prosecutors say Victor Disalvo wanted to confront Diaz about the relationship and went to Diaz's apartment.
Disalvo testified that during the confrontation, he shot Diaz when the victim lunged at him while holding an object that the defendant thought was a gun.
Diaz's family found the body on Christmas morning. Prosecutors say Disalvo was arrested after telling a friend that he was involved in Diaz's death.
He is scheduled to be sentenced on April 30.
AP contributed to this report.