It's easy to get overwhelmed emotionally, especially if you don't have strategies at the ready to manage how you're feeling.
Some of the strategies I use are:
allow myself time to reflect instead of react
deep breathing, in through the nose, hold, out through the mouth
if I said something careless: immediately apologize
if it's a relationship issue: think about things from the other person's perspective
if it's a work issue: allow time things to sort themselves out
changing my environment - inside to outside, work to coffee shop, etc.
listen more, talk less
How do you manage stress and emotions?