I'm not going to lie, I can tell you I would and say I'd be a good Christian, but in reality had I ever been a situation I'll be a human being like Apostle Peter, I'd probably let the c0ck thrice crow. 
To be honest though no offense but your situation wasn't as black and white as these motherfckerz. Yeah it could've been scary, but reality there was no barrel wielding in your face. There was no, will my kids and wife see me come home through those doors or will they see me come home through those doors in a coffin.
Self preservation is a gift from God (otherwise why'd he say we should 'value' life). I say preserve yourself so you can do more good, and sow more seeds of good. If we let c0cksvckers like those run rampant, others will only sow same things. Imagine then how much poor and meek they'll victimize.
Sometimes God call you to be the instrument of war; sometimes you just need to do it and let the Almighty sort them out.
Note I'm not asking to be 'actively' seeking evil, I'm saying if you were in the crossroad where evil put you in the spot between a rock and hard place, God I pray you choose yourself (your wife, your family, your friends, your life) and let'em have it.
If it ever was a sin, even in the back of your mind, at least you live another day to repent. 
"Praise be to the Lord my Rock,
who trains my hands for war,
my fingers for battle.
He is my loving God and my fortress,
my stronghold and my deliverer,
my shield, in whom I take refuge,
who subdues peoples under me." (Psalm 144:1-2)
Amen.
PS Sometimes, 'euthanasia' is a form of mercy.