Q1. ...Maybe.

With implied stakes so high, I would challenge my own belief system first..

For example:

To stand up for those who can't standup for themselves is a most noble cause, but can also be dangerous/wrong.

An animal has no voice , it can't be heard by those who mainly listen with words (humans). If an animal is threatened or hurt by humans, it makes sense to standup for the creature (if it was clearly a victim) as clearly it is an in justice to standby..I mean it can't possibly standup for itself?

However, in nature (natural system) things must learn to stick up for themselves to survive. Should I interfere with such a process, I maybe messing with nature. Take humans if someone is being picked on by someone else, say someone stronger and I smack the stronger person down..what did the weaker person learn?...it depends allot on the situation and how i interpret it.
To me once I am sure as I can be, what i am standing up for is true, I will stand up for it. It maybe possible that if I risk my life in the attempt, I have made the situation worse...I mean there are allot of big problems on this planet, if I threw myself in-front of a car to protect a confused animal, that put itself in harms way, I would no longer be around to influence the people who are trapped by the systems, that likely caused the animal being killed in the first place. I would try and try again to do what is right, if I was unable to make it happen, I would settle with influence it or others as much as I can to make a difference, it may take years!

..Great thought provoking question mate!

Q2. Yes and I did it!. the question for me now is what can I do about it. I mean I can't turn back time. The best I can do is regret my actions and honour the victim. I can't ever forget and will always regret, even if I made up for it 1000 times over I don't want to forget as it is a precious gift (even though I took it without asking and never should have done it), at the cost of another I learned an important lesson. To make mistakes is to be human. To learn from our mistakes and move on is part of nature. We must forgive ourselves for transgressions and not try to convince ourselves its ok to continue, instead we need to be strong and trust our inner voice and stop making excuses like... well everyone else does it...or I won't be cool if I don't participate! or people will judge me if I try to stop in justice...

A difficult question to answer - I will ponder some more.