(((granite))) I'm so sorry this happened to you and that you are feeling very scared and confused.
I hope someday you can allow yourself the option to feel that you 'can' talk to T. The more you tell yourself you 'can't', the more ingrained that becomes. You are scaring yourself. Not meaning to, of course, but that's what happens in the end.
It creates a kind of stalemate: T says granite, you can tell me anything/granite says I can tell T nothing.
This incident at work is a perfect event to tell T about. It's something real that happened and your fear is real. You can tell T about it and also tell T what you say in your post, that you feel like you can't tell real from not real sometimes.
What we say in therapy doesn't have to be huge, just a place to start that session. Our T needs to know us but it doesn't have to happen all at once. A little bit at a time is just fine.