This is my story, though I'd be interested to hear from others who have different but similar experiences:
My 5yo daughter doesn't melt down very often. If she doesn't get her way she usually protests and grumps, but usually doesn't melt down. When she does melt down (usually when she is tired, but very occasional at other times) she just yells and me and cries and screams. Oh, she tells me to "stop yelling!" (meaning I am saying something she doesn't want to hear) or to "say something!" (meaning something she wants to hear.) Many times this happens, I have the presence of mind to be patient and put it in perspective.
BUT I have this quirk when I am stressed, or in pain (or being yelled at) that I feel incapable of moving or thinking and I hate to be touched and cuddle until I stop feeling that way. I get in "get through this moment" mode and I can't even move mentally to find that place of patience and peace. I almost feel paralyzed, not with fear but just when dealing with the stress gets difficult, almost like I need to shutdown because of the overload. That might be OK, better than starting a real fight, but *if the yelling continues* I boil over I can react, but badly, yell sometimes (less often now and shorter duration but still I feel defeated when I react that way, in part because it soooo doesn't help). When dh is here, he can say, "don't say anything more" and be my external motivator and give me a few minutes to have my own time out. But when I'm alone I'm afraid I handle it poorly.
I'm not sure I can describe what I feel very well, but I know other mamas have moments like these and can throw some suggestions my way (even a juicy mantra for those moments of paralysis?), some sympathy, or at least share a similar story.