T.R. Knight Ties the Knot

T.R. Knight has married his longtime boyfriend.

A source confirms to PEOPLE that the former Grey’s Anatomy star wed his partner of three years, Patrick Leahy, on Friday.

One of the guests at the nuptials was Knight’s friend and former costar Katherine Heigl (their characters, George and Izzie, were also BFFs and at one point lovers on the show).

Heigl posted some pics on Twitter from the wedding, which took place in upstate New York. She wore a red lace dress to the nuptials, and goofed around in a photo booth with her husband, Josh Kelley, and former Grey’s costar Kate Walsh.

Knight, 40 – who’s currently starring in the off-Broadway production of Romeo & Juliet with William Hurt and Elizabeth Olsen – left Grey’s Anatomy in 2009.

He asked to be let out of his $14 million contract three years early after an incident on the set in 2007 when his co-star Isaiah Washington referred to him with an anti-gay slur during a heated argument with Patrick Dempsey.

Heigl defended Knight at the time, declaring, “T.R. is my best friend. I will throw down for that kid. I will beat you up. I will use every ounce of energy I have to take you down if you hurt his feelings.”

PHOTOS: My Wedding, My Way

• Reporting by JULIE JORDAN