If you know that being an ethical healthy vegan is the right and Godly way to live, then why are you torn?
You live the way you should as an example of the way we all should live, and let the others live the way they want, but not with your help in preparing non-vegan meals or buying non-vegan items. If others want your help or participation, they need to live according to your rules and not theirs.
In the Love of the Lord,
Frank and Mary