This argument doesn't make sense. Even if you do accept that NATO is not purely defensive because of what happened in Libya, blaming NATO for Russia invading another country that isn't in NATO makes as much sense as me blaming my brother John for the fact that my other brother Robert was beating his wife, and then violently taking it out on John.
And that's ignoring the reason NATO is expanding. It expands when new countries decide they want to join it. And countries at present are wanting to join it because they feel threatened by Russia. The reason for its expansion is Russia's aggression, so to turn back and blame NATO for Russia's aggression is completely backwards.
Nato expansion has always sounded dumb to me too. Nato is a defense pact, it doesn't ever attack so there is nothing for Russia to defend against. And if some countries were to attack Russia, them being in Nato is irrelevant since the other members won't help.
Russia is the only European country that violates others borders. Everyone else agreed that wars are dumb and joined a peaceful union called the 'EU' or at least has close ties with it. Now Russia of course could have joined the EU too, but Putin chose not to.
It started as some NATO member countries on the 19th of March. My understanding is that NATO later voted on it to become fully involved by the 24th and took over by the 31st. That's how NATO works - when a few members get involved, everyone else will follow.
Let's imagine a few NATO member countries start bombing Russia. If Russia strikes back, the NATO pact means that all of NATO becomes involved. That necessarily means that if any NATO member country is involved, all of NATO is involved. NATO is basically a shield for NATO member countries to do whatever they want, because if anyone fights back it triggers the whole alliance.