I was thinking too he might react violently but I think he's mad at Cersei for automatically blaming Tyrion for Joffrey's death. Cersei's hatred for Tyrion set in motion a series of events would have not gone well for the Lannisters (the fracturing of their family, Tywin's death, etc.)

And another thing.....did Jamie even like Joffrey? He clearly had feelings for Myrcella but Joffrey?

@RustyShackleworth said:

And another thing.....did Jamie even like Joffrey? He clearly had feelings for Myrcella but Joffrey?

Nobody but a mad(wo)man could like Joffrey. I don't think Jaime was blind to Joffrey's many, many flaws.

Jaime didn't have to kill Olenna. She was already going to die.