The "farce" Michael refers to was Carlo provoking a fight to lure Sonny out to his death.
It fooled Sonny.
And here all these years I thought the "farce" he was playing with his sister was the farce that they had a decent marriage, and that he was on the up and up. the basis for this is that it was Barzini who set Sonny up. Csrlo regualrly beat Connie, and this time he beat her so badly she called "home" for help. That was a set up, not the entire farce Carlo was playing.
I disagree.
Michael is telling Carlo why he's being punished. It's not for being a bad husband, but for complicity in Sonny's murder.
Plus, if Michael were referring to the bad marriage and Carlo's general shortcomings, he would have said "that farce you're playing," not "that farce you played." After all, they were still married.
