Welcome and thank you for your service. The others have given you a lot of good info. I have found Anthony's Cup analogy (in the notes - check it out) to be a big help. Because of our anger, it is sometimes hard for us to form complete thoughts, let alone complete sentences when we are overloaded. I have explained all this to my husband and now I only have to say, "My cup is full" and that is the cue that I need help. It might be that I need to unload about something emotional, or I just need help unloading the dishwasher. He just asks, "What can I do?"
Sometimes, I just need some alone time, and he doesn't get mad or offended, he just says, "Go for it" and takes care of the house for a few minutes, a few hours, or a few days, how ever long it takes me to snap back. I've learned a lot of good grounding technique here, so now it usually just takes me a few minutes, or maybe a half hour to get re-centered, but the most important thing is that he doesn't take it personally and knows that it has nothing to do with him.
Read as much of the stuff here as you can and share with your GF. Have her read it too if she can. It saves so much time and emotion since you don't have to try to explain things that sometimes you just can't. It has also freed my husband from the notion that he should try, or even could "fix" me. He now knows that he can, and does. help in a big way, but that this isn't his fault and is bigger than both of us. Rather than feeling hopeless, that is amazingly helpful as it actually outlines what his "job" is and he can do it, do it well, and not feel guilty or hopeless as far as his participation is concerned. I hope that made sense in some way.
Again, welcome and also to your GF who is now part of this silly family too.