How do you manage your emotions without being fake? How do you keep it inside without later exploding on someone?

I don't know how to explain it really to someone who can't. Just kinda learnwd or grown to be able to compartmentalize the anger until able to focus it into work or direct it at the culprit when it isn't disruptive to what needs to be done. Gotten pretty good at in as I grown older.
I'm not trying to say I'm better or anything. It's a strength that comes at a cost, it also kinda results in being seemingly cold and stand offish in other life facets.