I write and talk and teach a lot about how to help kids with their strong feeling. Of course, helping ourselves with our own strong feelings is important, too!
My best 'low tech' strategy is so ridiculously simple--just wait a while. If I can just do and say nothing about a feeling for a little while, it often passes. Some feelings, of course, need a response and I'm not thinking we just need to let everything go. But lots of my feelings seem so important and even urgent in the moment, and then 20 minutes later they seem kind of ridiculous.
Feelings don't only exist in the emotional realm. They cross right into our bodies, triggering stress hormones and a physical reaction to protect ourselves from perceived danger. When we're upset, we get flooded with chemicals that make us want to DO SOMETHING. A wise person can remember, feelings come and go. Waiting for even a minute can give the feeling time to pass. If you can wait 20-30 minutes, much of the physical response will dissipate and the more sensible 'you' is more likely to be back in charge.
I can get pretty emotional, and it really helps me to remember that feelings will pass just like clouds on a windy day, often without my doing anything.
As a mom (to 2 teenage sons), wife, and person in the world, I have been on a long imperfect journey. I have made many mistakes, but with mindfulness, emotional reflection, and lots of support I have learned enormously from those mistakes.