I've been in that space myself, just holding things in, until it gets so uncomfortable and hot I burst.
I think you should probably start by being honest, with yourself. If something really does bother you, accept that it bothers you, and write it down. A part of my internal changes have come from accepting that I am, in fact, bothered by certain things. I'm not stoic. I have pretended to be stoic from 6th grade up until age 20. Then I lost my mother. And the dam broke.
No one is safe. I do have a filter but if something needs to be said right away you damn right I'm saying it. Not only that, if you voice what's going on with you, people can know instead of assuming.
And clearly people do want to know. Trust in that.