Help with communication

Hello!! Please note I’m only asking this to practice until I am able to get an actual therapist! I am seeking one out!

So, I have an issue where if something bugs me I am terrified to express it to anyone. It’s become a bit of an issue, it was caused by a past ex who would shame me for communicating and turn things against me if I brought up a concern.

Any tips on what to try and practice until I can actually see someone?