My dad has had an addiction to alcohol for as long as I can remember. He's never been physically abusive but he's had times where he'd get verbally abusive to people around him and when he'd come down, he'd either regret it or not even remember that he said anything damaging at all. He was at his worst when he retired, and had so much time to himself, he'd be drunk to go pickup my mom from work, mind you, she gets off at like 2 am from downtown cleveland and has/had to wait for a bus to get home, it's riddled with homeless people and wasted people leaving bars/clubs. Their relationship is strained to say the least, but I assume neither of the two will call it quits for financial/property reasons.
He'll have periods where he's sober for months and is a joy to be around, nobody knows me better than him, but then he'll have times where he's goes on binges and is terrible to be around. He's missed out on concerts/recitals throughout my youth because of his drinking and he's pretty much the reason why I refuse to even take a sip of alcohol.
I've talked to him about it and why he does it, but all he says is that it makes him feel better (he's got bad arthritis) and that it masks the pain better than his prescriptions. Idk if that's the truth or not.