In this particular circumstance? Negotiated surrender. When NATO didn't line up on the border in equal or greater measure to the assembled Russian forces, it was either years of death and destruction or surrender.
It's about clarity of purpose in responding to the world as it is rather than as you wish it would be, even as it should be.
Putin is an evil bastard. Say it a thousand times, doesn't change a thing. Just because something should be different, because someone shouldn't murder hundreds of thousands of people, because someone should respect a people's autonomy...it makes no difference. Dying on principle is foolish enough, let alone asking others to do so.
Would there have been a purge? Surely. Would there have been thousands detained, imprisoned, tortured, killed? Likely, yes. Could that have been mitigated through diplomacy and exile? I believe, yes. Would it have been the scale of destruction and suffering seen over the last few years? Unequivocally, no.
Even "victory" at this point is a massive failure. There is no outcome that can justify this.
EDIT: I meant to say that I said all this in the days leading up to the current invasion, and continue to maintain my stance ever since. I get a lot of grief, from my close Romanian friends in particular. We had an argument about it with no resolution. It remains, to this day, a position that baffles them, and I don't expect that to change.