To me, she looked really angry. Since anger at the people who murdered her husband is a normal emotion in such circumstances, they probably just waited until she felt that way to film her remarks. She wanted to project strength to show the murderers their plan will backfire.

FYI, I was once being threatened by someone with a loaded shotgun… yet I was icy calm as I said to myself “I don’t think he’ll shoot me, but I suppose that’s what most people who get shot think.” I imagine some fear circuit in my brain was switched off as a survival instinct because calmness was my best hope. People don’t always react with the emotions you expect.