Russians and Ukrainians are the same ethnicity, the term ethnic Russians is just something Putin has pulled out of his anus in the last decade to try and justify his drive towards war.
When people talk about "pro-Russian" Ukrainians it usually refers to Ukrainians who prefer the country forming links with Russia over forming links with the EU/west, maybe even some who would prefer to form a USSR style union with Russia. It doesn't refer to Ukrainians who want Russia to conquer/annex the country (granted there will be some, but a negligible amount).
You must realise you are wrong by the simple fact, that you have a Ukrainian language and a Russian language. There are both Slavic languages (descended from proto-slavic) but they are not the same. Actually I suspect Ukrainian language is probably closer to Polish than it is to Russian.
I'm interested as to what
@Entai has to say as he apparently has a Ukrainian wife but I have a very good Ukrainian friend who lives in Boston and he will definitely correct your assertion that, "Russians and Ukrainians are the same ethnicity".
You might want read up on it as by calling them the 'same ethnicity' you are in fact saying exactly the same as Putin and Russian imperial propaganda. Putin said just that a few days ago in his pre-War statement.
Way to go unbersonic!