I’m not good with masking my emotions sometimes, although I do try to process the things before I take any action.
My face and body language on the other hand can reflect what I’m going through at the moment.
Are you aware of any ways to control yourself under difficult situations (apart from things like meditation) ?
Practice probably will help. If you can find a mirror while you’re in such a state, you could practice controlling your facial expressions in front of it.
That said, expressing emotion isn’t inherently bad, though I understand there may be some situations in which you don’t want to.