Is the Filioque church-dividing, or a resolvable misunderstanding?

The West confesses that the Spirit proceeds from the Father and the Son; the East confesses procession from the Father alone, through the Son. Both sides cite The Nicene Creed — and both accuse the other of misreading it.

Two questions worth separating:

1. The dogma — is double procession compatible with the monarchy of the Father?
2. The procedure — was it legitimate for the West to add to a conciliar creed unilaterally?

I suspect more agreement on (1) than the polemics suggest, and the real wound is (2). Persuade me otherwise.