We've been together for 3 yrs and worked hard on learning how to communicate and how to fight with eachother. We've even been twice to counseling. My gf carries some problems from her childhood with her, but overall she is a caring, sweet and loving person that I see a future with. But she can be really emotional. While I am a silent, chill dude.
We're moving to a new appartment (been living together for 1,5 yrs) with room for a child whenever we want to start. The issue started with receiving a message from our current landlord not granting us another week extra to stay in the current place after the notice period – so we'd have sufficient time to paint the new place and move out. My gf got mad about this, cause this might mean we won't be able to paint and she started saying it's partly my fault for texting the landlord wrong (acc to her). I should have told him we can't move out in time instead of asking if it was possible to stay longer. At this point I said that there's nothing now we can do about this, we are legally bound to leave and we need to move forward, but she's free to try talking to our current landlord herself (she's pissed that she wasn't included in the text where I asked the landlord – which I thought at the time was not that big of a deal).
The discussion flared up because she got really mad and started repeating this issue and verbally attacking me about it. At this point I also got upset and defensive. I'm normally not someone who gets angry quick, but usually whenever she gets angry there's another reason why she gets so upset. Something from work or family that's bothering her. When I asked an hour later if anything happened during the day which made her get mad so quickly (then I could understand why she acted this way) , she replied that it had been a good day. This ticked me off and we agreed to cool down for the rest of the night before talking things out.
So we just had a conversation and I told her that being verbally escalating and acting so angry with me is a boundary of mine. If she's really angry, go regulate yourself, take a step back, be angry in some other way. But don't start acting out on me instead of communicating the issue properly. I told her that this is where I draw a line, that she has every right to be upset, but she can't behave so strongly towards me like that. She kept saying that her emotions are valid, they can be present, and that I am rejecting her if I don't accept this. I told her that I do accept her emotions and her right of being angry, but it does not justify her behaviour towards me (neither does my defensive behaviour, I need to quit a conversation sooner when it's heating up).
Suddenly she asked if I still like her. I said, off course, but just understand that this is a boundary. She completely lost it (because of the 'yes, but' she told me afterwards – she has separation anxiety and is scared of 'conditional love') and started raising her voice again, yelling that I need to accept it, that I had to stop acting that her acting angry is such a big deal, that I don't know what it's like to be so angry and am the one that can't deal with it. Then she stormed to the kitchen to start grabbing diner out of a glass tray. Only she started hitting the spoon hard repeatedly in the glass. I walked to her wanting to tell her to stop acting like this (should've known better), but even before I could say 3 words she screamed I had to go away, leave her alone, that I was stupid of coming near her. I didn't recognize her, she was like possessed by some demon and started walking angry and yelling around the place. I've never seen this kind of outburst. (In the beginning of our relationship she did have smaller anger outbursts as well, but this stopped as we communicated better – there has really gone a lot of energy already in this part of our relationship).
I am really shocked by what I saw. She calmed down in 10 minutes and came to explain her reaction (at this point I was in the next room) and wished I hadn't seen her this way. That it'd been long since this happened again. That she fears I might doubt the relationship because of her emotions (her strong, fast-paced emotions combined with her overthinking have been an issue in the past). I didn't know how to reply, still processing what happened, and then she went away and cried. I'm still processing her behaviour I just witnessed. How does one go from here? This has impacted how I see her as a person.
TLDR: After a heated argument I told my gf my boundary, and during this conversation she became furious and had a very big outburst of anger that heavily shocked me.