it is very hard to definitively define what is right and what is wrong. there are things that are objectively wrong, but then many things that depend on the situation.
killing is wrong, unless it is unavoidable in self defense.
causing suffering is wrong, if it is unnecessary
there are many such things like that, but most can be covered by the above two rules.
in my view, for over 90% of the world population, eating any animal product is wrong, as it is a case of causing death and suffering unnecessarily. i think that this is an objective moral wrong, though almost everyone ignores this.
i think that generally, provided that you cause no suffering to anyone else, you are entitled to do as you please. but then, almost every action has consequences.
you could refer to mills harm theory that states that no one has the right to intervene with anything that you do (provided that you harm no one else) even if you are likely to harm yourself. paternalistic intervention is insuffient grounds.
anyways - you could argue that almost any action you take has consequence, so all actions are open to intervention. seeing as eating animal products has such a profound effect on so much, intervetion is perfecly justified.
intervetion could be any range of things. informing people of alternatives is one take - blowing up meat trucks is another. both are morally justified.
there is nothing wrong about feeling

madcat. i hate it that people think nothing of eating animal products, and despite my best efforts i do look down on them. even though i was once in the same situation, i no longer can understand how people can ignore animal suffering.
jonathan