my wife used to yell like that. would chase me around screaming. even escalated to physical violence, quite often at first.
what worked was consequences for her destructive behavior. my wife had abandonment issues, and the one thing that scared her the most was the thought that i was going to walk out and abandon her one day. her actions were like a self fulfilling prophecy. had it continued, i would have eventually left her.
i also had to have a vision of what kind of person i wanted to be. remembering that vision kept me on track.
eventually, i realized that it was never going to change unless i changed my own behaviors. basically, i did what unbelievable suggested to you. i provided consequences for her destructive behavior. i also avoided arguing anything that i could not know for certain, ie, her emotions, thoughts, and intentions.
that last bit was kinda important. you have said that she has a sharper wit than you when you two are arguing. as you have already identified, it is because of the fight or flight hormones. when you start to feel anxious, your brain is flooded with chemicals that make it very difficult for you to think. so, instead of trying to bolster yourself and think while your brain is locked in fight or flight mode, crystalize your whole argument strategy to simple truths that you know for certain, and don't argue anything else. in other words, don't say anything about what she intends, thinks, or feels. only defend your own mind, ie, your own thoughts and feelings.
instead of saying "when you do XYZ, it makes me feel like you want/feel/mean ABC", say "when you do XYZ, this is how i feel".
its an incredibly simple thing to say, and truth be told, is the only thing you really need to communicate anyway. most importantly, it is something you should be able to hold onto even if you are all amped up.
next, you need to provide consequences for her behavior. the number one consequence that you can provide for her is physical space. tell her upfront that if she gets in your face, you are going to leave for fifteen minutes(or however long you want) and will not speak to her until she calms down. check back in, if she yells at you again, leave again for another fifteen minutes. do this consistently until she learns that she simply will not be able to speak to you unless she is willing to be civil about it. if she suggests that you two resort to texting or writing notes to each other for a while, accept it. remember, its going to take a while for her to change her emotional responses to things as well. while you are away, practice things to get your body to produce more testosterone and less cortisol. things like exercise, pushups, meditation, or even laughing. practice then any time you feel anxious. here is a video to get you started with some ideas: https://www.ted.com/talks/amy_cuddy_...re?language=en
some of them, like a power pose, can be done pretty much anywhere and can even be done in public without people noticing what you are doing. i know because i have done them a lot. nobody has ever noticed that i was doing it, but pretty much everybody has noticed the change in my personality.
if she calls you a bad name, tell her that you will not tolerate such disrespect and will not talk to her for the rest of the day, or until she apologizes, whichever comes first. and then go out and buy a VAR and keep it on you the next time you speak to her. show it to her, let her know it is there, and tell her you want to be able to review your conversation with her to find out if you really deserve to be called the names that she calls you. after all, if she did not apologize, that means she must not have been in the wrong. maybe you said something you shouldn't have and she responded in kind. either way, with a VAR, you will have a record of her verbal abuse, and both of you will know it. the goal is not to catch her and gain dirt on her. the goal is to get her to practice moderating her own emotions and talking to you in a civilized manner. the more she forces herself to calm down, the better she will get at it.
another thing you should try is active listening, but don't even bother with it if she refuses to apologize for insulting you. until she is willing to admit that her behavior is wrong, she will likely only use your attempts at active listening as more fuel for her anger. she will see it as patronizing. if she is willing to apologize and admit that she did wrong by her treatment of you, then listen intently to what she says about how she feels, and paraphrase it back to her so that she knows that you were listening.
understand this, there is nothing wrong with you. the way you feel is not an indication of how strong or weak you are. think of it like this... i am a paratrooper. we jump out of perfectly good airplanes a lot. some of us are scared ****less when we jump, some of us are not bothered by it at all, but we all jump. everyone views us exactly the same so long as we all jump. we are not judged by our feelings at all, but rather by our actions. you are no different. you can be scared ****less and paralyzed, but if you can remember the action that you need to take, and then take that action, you are not weak. you are not spineless. if you state that you will walk away from her the next time she tries to intimidate you, and you actually manage to do it, you are not weak. you are not spineless. you are not Casper Milquetoast. you are a someone who has stated how they wish to be addressed, stated a consequence for refusing to address them in such a manner, and followed through with the consequence.
don't ever say you are going to do something unless you are willing to do it. if your partner wanted to keep you around and you told her that you would immediately start separation proceedings the next time she insults you, she likely wouldn't believe you today. if, however, you plainly state each action you are going to make and follow through with all of them over the next couple months, she will likely believe it. after all, if you have meant absolutely everything that you have said, and proven that you meant it by actually doing it, why wouldn't she believe you? this goes back to that vision of who you want to be... do you want to be the kind of person who makes empty threats whenever they feel they are not in control, or do you want to be the kind of person who clearly and openly decides exactly how they will act? do you want to be someone who attempts to try and control that which cannot be controlled, or someone who exerts complete control over their own actions, regardless of their fleeting emotions?
personally, i like to be in control of myself.
eventually, if you stand up for yourself enough in a consistent form, you will start to notice that you are feeling less and less anxious. you will know that even if your partner does blow up in your face, its not that big of a deal. you can put an end to it as easily as walking out the door. because, lets make something clear, you didn't really ask for advice about how to fix your relationship. you asked for advice on how to fix yourself.