Good morning, Phenyx. Regrets for the long-delayed response, but life kept intervening to thwart my good intentions.
The short answer is: no, this person's behavior is not acceptable, not excusable and not healthy. If you accept, excuse or permit it, you are reinforcing it. It is prelude to self-loathing on the sub's part and a miserable, failed relationship (again, from her perspective).
your next obligation is to determine, so far as you are able, the source of the dysfunction and your best response to it. I can imagine three possible sources:
1. your Dominant is somewhat clueless. It happens. By that I mean, he, like you, is just now beginning to understand and value his own dominant nature, just as you once discovered your nature. In doing that, we're often largely clueless and make horrendous mistakes. Some of us are deeply reflective in the wake of those mistakes, others externalize the blame ("it was her fault") in order to provide a fragile ego. A clueless, but otherwise good, person needs to be guided toward the appropriate clue supply. That guidance works best if it's non-threatening and focuses on specific behaviors (for example, creation of a safeword) that takes the worst edge off things. A successful experience in negotiating and rewarding one behavior sets the ground for negotiating others.
In communicating with submissives, for example, I will articulate a rule on a matter than I believe is important but not terribly intrusive. For example, the circuit-breaker rule might be "if I type your name and hit <enter>, you will immediately stop all activity, breathe, and type the words 'yes, Sir?'." she's then responsible for repeating the rule back exactly, and explicitly committing to obey it. We use the circuit-breaker to interrupt a downward spiral, so I'll test it a few times in the following days. When she gets it right, I acknowledge that fact and compliment her. With time, then, we build a repertoire of shared expectations and strategies. you might attempt some version of the same with a dominant partner.
2. your Dominant is emotionally unstable. Some people (my predecessor at my current job had a tendency to throw furniture and curse when he felt that his plans had been frustrated) have real anger management issues. It is possible that that's the problem, assuming that his other behaviors are not dysfunctional. There's a whole literature on how to deal with uncontrolled anger; I mostly avoid such people, in part because my own temper is both volcanic and dormant. It it needs to be the former, I want to be sure to maintain the latter.
3. your Dominant is a psychopath. Given your two notes (this one and the other on orgasm denial), the prospect is rather more than 50/50 that he is. The literature here is fascinating and disturbing. At base, a psychopath is an utterly charming bastard. Some people distinguish a sociopath (someone who has limited self control and absolutely no concern for the feelings of others, the sort of person who would watch a puppy drown because saving it was a hassle) from a psychopath (someone who has limited self control and who delights in controlling and damaging others). A sociopath has no clue about what "being nice" to another person mean. A psychopath has learned to use "being nice" (attentive, charming, caring) only as a ploy for heightening their ability to extend their control and deepen the damage.
Search the phrase "the charming psychopath" for a decent Psychology Today (1994) article on the subject. For a more-recent tool, you might look at a simple discussion of the Hare Psychopathology checklist. For each of 20 traits, you rank an individual on a scale of 0 (never), 1 (rarely), 2 (frequently), 3 (continually). A score anyway about the mid-20s puts you in the danger zone. All of the literature, though, does get back to the same point: psychopaths are predators who are freakishly skilled at charming you and sucking you in, slicing you open, drawing you back, and slicing you again. (Not surprisingly, CEOs, surgeons, TV personalities, chefs and lawyers are among the professions whose practitioners score relatively high on psychopathology scales.)
you might choose to negotiate with the dominant over these issues, but you absolutely must understand what's called your BATNA. That is, Best Alternative To a Negotiated Agreement. One of your sisters, and one of the Library's best authors, lovelyandsad is far better positioned to explain this stuff than I am since she's really smart, has read the lit and has honed these skills. Perhaps she'll clean this up: the short version is that you need to decide, in advance, what course serves your best interest if negotiations break down and your every interest is frustrated. The simplest BATNA might be "i will walk away, blocking Him here and on IM."
The bottom line is this: He may think of you as an object for His amusement. you are not. Do not act like you act and do not permit Him to treat you like you are.
Solis