Hi Alicia. Welcome to Psych Central. I am so sorry your son has so much anxiety and fear. He sounds really terrified. I would strongly suggest professional help like a therapist that deals with childhood trauma.

If this is not possible, you can write a letter to volunteer therapists who answer inquiries as their time allows. Here is link https://psychcentral.com/ask-the-therapist/

These articles may be of interest.
https://psychcentral.com/lib/tips-fo...ental-illness/

https://psychcentral.com/lib/sensiti...icant-anxiety/

https://psychcentral.com/lib/parenti...port-children/

https://psychcentral.com/blog/archiv...anxious-cycle/

The other thing to keep in mind is self care when we must cope with a relative or child with a challenge. This can mean for you getting therapy, exercising, doing creative things, and trying to create space where you can be you.