I'm sure it can be hard not to turn to physical aggression and violence when feelings get overwhelming, it's primal and instinctual, but it is also socially unacceptable.
1) If she isn't already, start meditating for 5-30 minutes/day, ideally morning and evening, but just evening works. This helps to give a sense of control and stability, and to learn how to feel emotions whilst also being able to observe them calmly. It really does help with reducing anxiety and improving motivation.
2) Work out everyday if she isn't already, ideally both cardio and resistance. It doesn't have to be a lot in the beginning, it can be a 30 minute bike ride and 20 pushups, but it's enough to raise your heart rate and get you out of your head, which reduces anxiety and aggression. It helps to consider active tasks that involve all of your focus to be a state of active meditation, like surfing, riding a bike, paddleboarding, that kind of thing. This is just anecdotal, but I've found exercise like this to really help with trauma and anger issues, and
others have too.
3) FIX YOUR FUCKING DIET!! I don't care who you are or what you eat, I guarantee you can be eating better. When you are PMSing, your serotonin plummets, and what temporarily bumps serotonin? Shit food. Sugar, carbs, heavily processed garbage I wouldn't feed my dog, cut all that out. It will make her feel better at first, but the issue is that most of your
serotonin is made in your bowels, and if she eats like shit, she will feel like shit. No pun intended. So put aside all those sweets and breads, eat just meat, cheese, nuts, mushrooms, full-fat yogurt, fruit, and vegetables. If she doesn't already cook at home, it can be a very rewarding skill to learn, and you can eventually start preparing all of your meals on sunday night and just eat leftovers throughout the week to save time. It sounds like a lot of work, changing your diet CAN be hard, but I promise it's worth it.
3.5) Take magnesium, vitamin D (if she doesn't work outside), B-complex vitamins, especially before and whilst menstruating. These helped with my mood, and the magnesium helps a lot with cramps and inflammation.
4) Don't repress your emotions. When you're angry, instead find an acceptable outlet, do pushups or go for a walk, which will get the adrenaline dump "out", and will also make you physically stronger, which is always a bonus.
5) Practice "box breathing" whenever you have a free moment. This is an example of bio-feedback, basically tricking your body into being calm and reducing cortisol. Breath in for four seconds, hold for four seconds, exhale for four seconds, hold (empty) for four seconds, inhale and repeat.
I mean this in the nicest way possible, but anger really is a state of mind. You can learn to manage it through discipline, exercise, meditation.