Yeah, Cersei set up Robert, but didn't Jamie finish him off? Anyhow, I'm not sure if people found out about that anyway, but since they kept calling him kingslayer, I assumed they knew.

Man, tell me about Tywin. Cersei's first husband said another woman's name during sex, just imagine how sex would be if she marries Tyrell. Tyrion got the sweeter part of the deal really.