Setting limits to agressive people after PTSD


I am brand new to this program and very happy to begin :-).

I am recovering from PTSD, and I have issues settings limits to agressive people (that remind me of my father). When some people agress or yell at me (a colleague at work), I feel paralysed. I can’t say those simple words : if you talk to me, I will leave the meeting. I managed 2 weeks ago to send a factual email to my manager and HR department to speak up about the situation going on for 2 years with this female colleague. She has since calmed down.

However, I still feel anxious at the thought of seeing her, I sleep very badly and am very tired, always on my guards at word, fearing what she would say go me.

I have automatic thoughts like :
She is going to attack me, she’s after me, I am in danger, I have done something wrong, I can’t move, I am scared.
I use tools like breathing techniques, visualisation, and say to myself “she’s feeling bad, she’ll nerver change, I have compassion for her”, but I did not manage to really feel safe when she’s here.

I am mostly scared to encounter the same situation again and again with people who see my weakness.

How can I manage to handle agressive people when my brain has automatic fight or flight response ?

Best regards