I can work with that. I'll just come up with some vaguely scientific explanation to make you last longer, but you'll still only have a couple of minutes after being cut in half. (Unless you wanted a variant that actually has both of your halves connected to some kind of machines to keep you alive for longer, and you'd only die after that machine is turned off)
But I need a few more things: For one, what perspective should I write from? 1st-person ("I"), 2nd-person ("You"), or 3rd-person ("he/she")? But I take it, from the PoV of the victim, that is, you, either way, right?
Also care to describe yourself (or more specifically, the character representing you in the story) just a bit? At least a little bit of 'your' looks, what name/age your character is supposed to have, something like that.
Similarly, are the other two partners supposed to have any particular physical or personality traits, or should I just come up with something standard?