My Good Friend's Marriage

Don and I worked with Ella in the same office in Singapore. When Don and Ella married, I was his best man and was introduced to Ella's best friend, Celeste. Later I watched helplessly as their marriage spiralled out of control because of Don's affair with a Chinese colleague. My attempts to comfort Ella led to more than friendship. How could I reconcile my feelings for Celeste and my lust for Ella?