What we saw in ENT was a 2,000 year old katra memory, and thus perhaps it could be excused as distorted or impressionistic.
I seem to recall that there was an account from the time of Surak in William Rotsler's Star Trek II Short Stories
that was a closer fit to what we saw in canon - at least, it had a war between Vulcans and proto-Romulans on Vulcan.
It's also worth pointing out that in her TNG novel Intellivore
, Diane Duane refers to the Sundering as told in The Romulan Way
and Spock's World
as one of many legends about the ancient Vulcan/Romulan split - she even gets some of the details about it (intentionally?) wrong, like the number of ships sent.