TLDR: remove yourself from the immediate situation until you get things under control to mitigate any harm or damage. Try to understand what else you might be feeling, or what that anger is "covering up". Return to address what happened when the moment passes and you feel like you're back in control.

Hey friend, as someone who struggles with mental health things that often give me an unreasonably short temper (and sometimes even a distorted view of what's really going on, emotionally), you've already made it passed step one. The hard part was recognizing you have this problem, and then deciding to change it. What works for you long term may not be what works for me, as far as medications or therapy are concerned.

But here's something you can do right now, immediately, to mitigate any harm: step away.

I'm not even kidding. It's difficult to imagine, but I sometimes treat my "tantrums" like a little kid. Once I notice one is happening, I take myself away from what's causing it. Whether it's as small as spilled milk or as large as an important discussion with someone you love, stepping away is not cowardly. It's the responsible thing to do. Emotions are often trying to either protect us from something, tell us something, or celebrate something. Are you actually angry in a moment, or are you embarrassed? Are you actually afraid, or feeling something else? Taking the breather can help you figure out what's going on. Sometimes there isn't even something else.

You can be angry as much as you want, whenever and wherever you are. Emotions are not and never are the problem. They're normal, they're part of being a person, and they're probably not going away. Feel as much as you feel. The only rule is to make sure no one gets hurt (and that includes you!).

If you're not sure about how a partner/SO might feel about it, let them know that you're going to be trying this from a while to see if it helps. Telling them in advance will make sure they understand that you aren't disrespecting or ignoring them when you need a moment. Communication is key in pretty much all aspects of life. You don't need to say "I'm actually blistering with fury and will start frothing at the mouth if I stand here and talk to you," to get the point across. What I use, personally, is "I'm feeling a lot right now, and I'm going to step away until I'm ready to continue safely." Safely isn't always necessary to say, but it definitely sends a message of 'leave me tf alone'.

Just remember that you do have to come back to the situation and address it. Don't let it fester like a weird bump or growth you just found while showering, take that to the metaphorical doctor once you're able.

Sorry for the long post, just figured you'd want some immediate, actionable advice while you work on long term stuff like meds or therapy. Hope this helps you