No, you didn't. All you did was say you don't believe Russia wants to control all of Ukraine. For one, they're invading all of Ukraine, not just part of it. For another, they're doing it to stop Ukraine from joining NATO, which is an attempt to control Ukraine, not just part of it. And then you gave an inaccurate recap of Ukraine's relationship with NATO and implied there was something fishy about them "suddenly" wanting to join, even though it wasn't sudden, and there's nothin fishy about wanting protection from a country that is now currently invading you.
None of that proved me wrong in any way.
But we wouldn't be forced to defend them. Russia is doing this now because they don't want Ukraine to join, because Putin knows if they join, he can't attack anymore, unless he wants to risk WWIII. Notice how he doesn't go after any actual NATO countries, just ones that want to join. Besides, this is pretty selfish. I'm all for requiring Ukraine to meet some standards before joining, but to say "Nah, you're on your own. Good luck with Russia" is pretty heartless. But then, I guess that is the conservative platform these days.