Tyrus thinks that everyone will turn on him. He sort of accepts this, because he has internalized that he is basically a bad person who wants to be a good person. He figures they'll hate him and he deserves it.

But he'll make the world a better place and they'll see that, some day.

He hasn't actually considered trying to calmly explain to Travis's friends what he did, why he did it, or that he's sorry. He doesn't have much faith in himself (or them, really) in that regard.

Did Harriet suspect at all before she left to Zen?