Ummm, call me a sissy but I rather think murdering people, even in imagination in the privacy of your own home, who upset me is a bit old-fashioned. When we were allowed to wear swords in public it was of course the done thing to slay those who wrong you on the spot (I am told there are certain states in the US where this is still allowed so if you live in one of those just ignore me). I would rather think over why am I so upset over what in the great order of things are generally trivial.

Some, many, people treat you unfairly, are nasty and inconsiderate and getting into a rage hurts you more than them. You cannot stop this, it happens to everyone, and unless there is a constructive response open to you, it just has to be shrugged off as 'life'.

As for your diary, just put a disclaimer at the front: "All thoughts, actions, names, places and people are fictional and any similarity to actual thoughts, actions, names, places and people are coincidental". Any halfway decent lawyer should get you off on that.