no, we are not going to forget it but we should not act hastily either, it will just make matters worse.
The reason Putin can do what he did is because the Russian generals and a sizeable chunk of the Russian population support his action.
We have to unite as many countries as possible to confront him. On this, the EU is the natural leader because Putin's action affect the 27 EU countries directly. However, the EU has only a budget, not an army. It is now clear that it will need an army or at least an air force and nuclear deterrent but that will take time.
I think Ukraine will be partitioned. Western Ukraine will need EU's protection so it will have to deal with the usual conditions: adoption of EU human right convention, adoption of the Euro etc. The wall between East and West Ukraine will come down in time, all for a better Europe in due course.