In your reasoning you miss one important point: the US broke their promise that they would not move NATO to the east anymore.
Ukraine was on the brink of setting up NATO military bases that would point their missiles in the direction of Russia.
The US has already placed a number of bio laboratories in Ukraine that were developing biological weapons against Russia.
CIA has been executing massive information campaigns in Ukraine for at least 10 years that turned Ukraine into anti Russia. As a result masses of Ukrainian population have started hating Russia even before the war started.
Every single day any Ukrainian citizen watching TV was bomparded by anti Russian hate.
What could Putin do with all that threat?
You yourself admitted that such a promise, if it existed at all, was given in a private conversation to the first and last president of the USSR, Gorbachev, and therefore such a promise does not have any legal consequences for states.
And such a promise could not even be fulfilled in principle, since according to Article 10 of the North Atlantic Treaty establishing NATO, “The Contracting Parties may, by general consent, invite any other European state capable of developing the principles of this Treaty and making its contribution to the security of the North Atlantic region to join to this Agreement." This means that any European state at any time has the right to express a desire to become a new NATO member, and this issue is decided by all NATO member states, and not just the United States. The US representative had no right to make such a promise, since it was obviously impossible to fulfill.
What did Russia achieve by attacking Ukraine and trying to destroy it? Because of this attack, Sweden and Finland became new members of NATO, and Ukraine will join this alliance no later than the end of the war and will definitely direct its missiles towards Russia as its most dangerous neighbor.
And your information that even before the war hatred of Russians was incited in Ukraine is nothing more than the fantasies of Kremlin propagandists, who somehow needed to explain to their citizens the reason for the attack on Ukraine. And now this hatred really exists and it is growing, as the Russian occupiers continue to invade the territory of Ukraine and continue to kill its citizens.