Hi, and welcome! I wouldn't call him "functioning"--we are way more than our jobs, and it sounds like the job is about the only thing he has left, besides the booze. And the job won't last forever if he keeps it up.
The abuse is a separate thing from the alcoholism. Alcohol won't make someone nonviolent, violent. Alcoholism really IS a disease, and it DOES make people behave selfishly, but not abusively unless they have that innate sense of entitlement that abusers have.
I'm so glad you and your kids got out safely. His dad's death is tragic, but it didn't cause his alcoholism. There can be a genetic element to it, though, so that might have been a factor. It's pretty much irrelevant, at this point, how he got there.
Are you and the kids getting any help, yourselves? Al-Anon (and Alateen, for the kids) are great programs to help free yourself of some of that anger you're carrying around. That's not to say you don't have plenty to be angry about, but the anger is costing YOU at this point--not him.