You should pay attention to what Russians are saying and what they are doing and imagine possible scenarios.

They are clear that they would use nuclear weapons only when there is a threat to the safety of Russia. Will they ask you when there is or is not a real threat to Russia? No, they will decide based on their criteria. They already acted because they believe that Ukraine not being under their control is a threat to the safety of Russia.

Ergo, any other outcome besides the capitulation of Ukraine is the threat to Russia. Any our help to Ukraine is the threat to Russia, as soon as it is effective enough to prevent Russia from conquering Ukraine.