Wedding bells rung on Grey’s Anatomy’s second to last episode of the season, but they weren’t ringing for Derek and Meredith.

Spoilers After The Jump!

Grey’s Anatomy fans have been waiting for Meredith Grey (Ellen Pompeo) and Derek Shepherd’s (Patrick Dempsey) highly anticipated wedding — but in a shocking turn of events on Thursday it was Katherine Heigl’s character Izzie Stevens who walked down the aisle to marry Alex Karev, played by Justin Chambers.

“You never know the biggest day of your life is going to be the biggest,” Izzie said during the show’s opening. “It’s the regular days the ones that start out normal, those are the days that end up being the biggest. Today was the wedding. It was beautiful, perfect.”

“Today’s the day my life begins. All my life I’ve been just me, just a smart mouthed kid. Today I become a man, today I become a husband,” Alex said as he married Izzie, who had the wedding sprung on her by her friends. “Today I become accountable to someone other than myself. Today I become accountable to you, to our future… No matter what happens, I’ll be ready, for anything, for everything… Today, Izzie Stevens, our life begins and I for one can’t wait.”

By the end of last night’s 100th episode, Izzie had lost her hair and appeared deathly pale from the aggressive cancer that has left her fate — and that of the actress who plays her — hanging in the balance.