All I know is, having to move living place and location has always been one of my biggest, deepest stresses and fears. Even though, as it's turned out, I've had to make a lot of moves in my life, some of them even really massive ones.
The first time I had to move house, I was 20 and living with my parents in the only house I'd ever known, the one I'd grown up in. They had to downsize to a smaller house not far away, for financial reasons/big loss of income. The idea of leaving the only home I'd ever known made me react as if someone had just told me I had cancer, or that my parents were going to die. It felt like a complete catastrophe and was emotionally very disturbing to me.
Of course, I had no choice and I adjusted to the move, but I had to use techniques that calmed me, like reassuring myself that if I liked my new room then I was going to be fine. Stuff like that.
As life turned out, I had to move a lot, especially in the last few years due to a life upheaval, and to be perfectly honest, even though I'm now a grown woman, these recent moves have devastated me. But to be clear, they took place under traumatic circumstances. I'm settled again now but it was stressful.
I completely understand your dread and fear in the idea of changing locations completely, because it's something I don't handle well either.
However, having had two different "types" of experiences of having to move -- the kind where it's done in a positive and controlled manner, where you get help in adjusting, and the kind where it's traumatic and forced, I now know that although both cause stress for me, the first type is definitely preferable and the stress dissipates quickly, at least it did for me. Almost like the good move is just a scratch and a Band Aid will do it, but the bad move is a more serious injury.
And even though any move, even a happy, nicely executed one, is upsetting to me, I know that the nicely done ones were a whole lot less upsetting, and you can get through those and even enjoy the change in the end.
So, if you are being helped and supported by family members who are welcoming you to your new situation, even though you will find just the thought of it stressful, you may also find that it all turns out okay with no lasting problems, and you may even like your new situation. Be glad it's not under horrible circumstances like some of mine have been! But yes, I still totally get your anxiety.
Is there anything you can do for yourself to calm your fears, like the way I had to focus on how much I liked my new room, when I was young?
If you can visit the new town and make a project of exploring it to discover places that might become favorite spots to go. Find out which stores will be your regular ones. Find out what your new living accommodations might be like, etc.
Anything that might be a "light at the end of the tunnel" for you in terms of finding any upsides, positives, practical things you might enjoy or find to be an improvement in your life. Sometimes you have to hang onto even the tiniest rays of hope when a situation is stressful and fearful. Small things to look forward to can help get your through what's upsetting about the general situation.