Listening to the argument all the way through, I don't think I've ever had so much genuine hatred towards someone I've never personally met, and I one hundred percent believe that Vito is a manipulative narcissistic abuser based on how he conducted himself throughout, as I will now explain.
1. He never admits to wrongdoing when confronted with legitimate complaints about his conduct. He tries to deflect and justify his shit attitude towards their fans, and when that doesn't work he tries throwing out hollow promises to stop acting like a spaz. That's the behavior of a boyfriend/spouse who's being confronted about habits he knows he can't defend but still wants to engage in, so they throw out superficial promises of change to try and shelve the issue, not because they feel remorse but because they don't want to deal with the stress of being dressed down anymore. On top of that, he pretends to meet them halfway by saying shit like "I can see how you might've seen it that way, but from MY perspective my actions seemed like the right thing to do at the time."
2. He keeps trying to barter with Dax by asking what he needs to do to get back in his good graces. He doesn't intend to actually follow up on requests made of him, because the point of asking him those questions is to give the impression that he's open to change. As we saw, he didn't even try to take Dax's advice to stop being a douchebag to their fans on Twitter and went right back to picking fights after the show.
3. He refuses to respect any boundaries set by Dax. Dax flat out tells him to NEVER call his wife for any reason and is clearly still angry about it, but Vito acts surprised and keeps trying to rationalize his decision to do so. His lack of respect for boundaries extends to his whiney attitude towards not being allowed in the studio anymore, because he feels entitles to be in Dax's orbit whenever he pleases. Speaking of which...
4. He's EXTREMELY needy and entitled. Having to abide by Dax's boundaries is a clear bother for Vito. He's genuinely confused to why someone might take issue with him blowing up their phone for a week because he thinks that being friends means he should have constant access to their time and attention.
5. When all else fails, he tries to manipulate Dax by appealing to his sense of pity. He initially tries to "talk things out," which in Vito speak it means "if I talk to you long enough, eventually I'll stumble onto the right words you want me to say and you won't be mad at me anymore." When Dax doesn't relent, he starts to whine and wane about how he doesn't want the show to end and how much Dick means to him, and how they have such a good thing going with The Biggest Problem, blah blah blah.
ALL of this fits into the category of manipulative and narcissistic, but what about abusive? The answer to that is simple: anyone who listened to that whole back and forth, listen to Vito and tell me you can't perfectly envision him trying to pull that shit on a girlfriend or spouse after doing something heinous. Tell me you can't see him talking with her over the phone and trying to explain that him joking about raping her little sister on his podcast was perfectly cool because he's a comedian and inviting her out to eat so they can "find a middle ground." I always assumed that allegation of him beating on a woman was true, but listening to him on that audio clinched it in my mind. He's the kind of person to cheat on a girl, get frustrated when she won't immediately forgive him, have a tard rage, and then try to smooth things over by trying to convince them that he just doesn't know any better before promising to do better.