I am sorry you are going through this. It all sounds like it has been very anxiety-provoking.
I think you are doing a good job of differentiating which things were from your ex and how your current friend is not doing anything to trigger these feelings.
It surely sounds like you were somewhat traumatized by the former relationship?
It sounds like you can trust the process with your new friend. You may find it helpful to work on interrupting your anxiety?
Try to be very Present within each moment of your life each day.
if you need more help with anxiety, you might benefit from seeing a therapist?
Please take care of yourself.

WC