WTBH, like they say, when we know better, we do better. When you "protected" him all those times, it was likely b/c you didn't know any better.
Interesting that you jumped thru all those hoops to keep people from "finding out about his problem" and now it turns out that people knew anyway, right?
And bottom line to ALL of it? HE is the one who made all of those bad decisions. You didn't force him into any of it. And it was never your job to prevent it, whether by covering up for him or by NOT covering up for him.
I hope your feeling of guilt and shame about his antics passes soon.