I want to talk to someone but I'm scared they'll judge me

There's stuff I've been carrying for months — stuff I haven't said out loud to anyone. Every time I almost share, I imagine the look on their face or the awkward silence after. I grew up being told to keep private things private, and old habits die hard. I know bottling it up isn't working because I'm snapping at people over small things. I just don't know how to start without oversharing or shutting down mid-sentence. How did you take that first step?