I too have no addictions in my family nor did I ever grow up around it.
Yes, the label "codependent" is thrown around too much. Most behaviours are human and most humans are codepedent.
My ex and I didn't make it, but I've seen MANY that have and went on to great lives and relationships. The key is for two people to be working a program though.
I'm sure some have made it without a program, but I've not met any since the ones I meet are only in meetings.
The abuse is common, the denial much more common. My ex was (is) a loving guy and he stopped drinking. He's a loving Dad, but he struggled with his demons and intentionally and unintentionally was abusive.
I struggle with codependency behaviours so was also abusive to a point.
My ex also showed very little remorse when I caught him cheating. Not sure why there is this lack of remorse, but I think it's because addicts cannot process shame well.
They accuse and blame to divert attention away from their actions.
In either case, the key is to get well yourself and he either follows or doesn't.
The success stories I heard were all based on this premise