I find excercise helpful or even just going for a walk.
I find it really important to take some time away from any situation where I realise im having an extreme reaction, before deciding on any course of action. I would then try to think through what has triggered the extreme reaction and how I might address that issue.
I have discovered that a lot of the time its about meeting your own needs. Are you tired? Hungry? Cold etc etc this seems really basic but cab effect your ability to regulate emotions massively so always consider those things and addresing those first if you can.
I attend a mindfulness session every week which I find helpful.
Just basically about focusing your attention away from your own thoughts. Finding states that make you feel calm.
I find talking to myself in words in my head like im a separate person often helps.
Such as 'you are feeling very extreme anger right now do you know why? Its because my husband ignored me when I was speaking to him. Why has that made you so angry? It reminds me of my childhood. It makes me feel unloved and rejected. I feel humiliated and worthless. Do you think your husband meant to hurt you? No but he did. What do you think you could do? I could calmly tell him he has hurt me. Are you prepared that he may not be able to make you feel better as he may be in a bad mood himself and may not give you the validation you need? No I think that would make me more angry. Then what could you do? I could leave the situation and stand outside and look at the trees waving in the wind until I feel calmer. Im not really angry im sad. Im also tired and hungry. I dont want to make things worse by behaving in an angry way and saying things I dont mean. It wont make me feel better in the long run' etc etc
That often helps to just talk really simply through to myself what is happening
Doesn't always work.
I find it have to have awareness before hand about what might cause me to be unregulated and make plans to tackle that.
I know I struggle with crowds, loud noise, heat, waiting for things in line or buses or appointments, having to interact with strangers etc
So id make plans for what id do if I start to get distressed.
Another thing I looked into was body positions and sensations. So it can help to behave physically in a calm way. Such as relaxing your shoulders, having open palms, sucking a sweet or chewing something, slow breaths in through your nose and out through your mouth etc