When Caitlin bought Joey's house from Sydney
Here's what I think could have also been said in the part of the episode, Time Stands Still where Caitlin stopped by Sydney's office and bought Joey's house from her;
Caitlin Ryan: Sydney, I'd really like to talk about what happened last Christmas.
Sydney: Oh god. We're doing this. Okay, Caitlin, give it your best shot.
Caitlin Ryan: I'm really sorry, Sydney. I wish I could have sorted out my feelings for Joey sooner and I know I hurt you. I was wrong.
Sydney: Look, Caitlin, I was just mad and embarrassed when Joe dumped me for you. It has been really hard on me for a while but if you hadn't spoiled all of the time and effort that I put into my relationship with Joe, I would have stayed in a relationship with a man who wasn't really in love with me and I'm glad I found out before we went any further in that relationship.
Caitlin Ryan: Thank you for being so good to me, Sydney. You have every right not to be.
Sydney: I'm happy, Caitlin and I'm in a better place now and I'm so glad you and Joe are so happy together too.
Caitlin Ryan: Thank you, Sydney.