I appreciate that you are willing to engage on the topic respectfully. And you ask good questions.
I have spent some time pondering the choice of veganism vs meat eating vs vegetarianism in the past.
I agree it is important to examine one's emotional reactions. That is how, ultimately, I left behind religion. And that experience is what colors my view and provides the answer to my reaction.
To wit, one of the (many) things that I chafed against was people dictating to me what my morality must be as if they are the final arbiters of absolute morality. It is one thing to disagree, to share your own morality, to state your beliefs. To state what the other person must believe, that is what I find annoying.
It's an interesting topic because one then has to ask, what is the difference between this and me arguing with a bigot? I believe very strongly that people are all on equal footing and of equal regardless of skin color, ethnicity, gender identity / expression, etc.
So how do I engage with racists...and why? E.g., Is it to change their minds? I mean that would be nice. But really it is to make certain their viewpoint never goes unchallenged.
And if I am morally reprehensible to a vegan, does that give them the right to challenge me? Yes. Does it give them the right to tell me what my morality must be? Hmm. If yes then I have the right to tell bigots what their morality must be too and I haven't grounds for complaint if someone does this to me. If no, then I may need to engage differently with bigots.
Now I could argue "but I am right about bigotry" and "being omnivorous isn't actually wrong" ... But that's from my perspective. I'm trying to step out of my belief system to look at this.
It isn't the scientific facts that are an issue; I am aware of them and don't dispute them. I have no qualms about reducing or eliminating most of the meat industry based on its environmental impacts. And I do wish to reduce my meat consumption on those grounds, not on moral grounds.