Allright, you've been bitten, however careful you were, however badass you may be, you were bitten, we're going to go with the 24 hour virus type (Solanum), what are you going to do with the rest of your life?
Go out with a literal bang. Attract as many as possible and cause a massive explosion that would at least thin the herd by a good fraction. The last thing I would do would be allow myself to come back in any way shape or form and cause any harm to any one breathing.
If none of that was possible chamber a round hand of the magazine and step outside.
I'm going to spend my remaining time with the love of my life. Perhaps at the last moments of my life, I will go out fighting. Whatever base of operations I'm at, I will walk out the frount gates, with guns blazing. Take as many undead bastards as I can, in hopes of saving the few humans I love...