It seems like a lot of people here relate to having experienced disappointment, fear and anxiety about relocating, being far from home, etc., when it comes to internship and/or postdoc. I won't repeat all of that but will only say that I've seen plenty of people go through those things as well. You're the only one who can reframe this situation somehow and I think there has been some good advice on how to look at it differently - in a way I can relate to what you're going through, there, or at least I could at one time. I didn't relish the idea that I might have to move for internship, but I went through a pretty radical cognitive shift as I was submitting applications and, that fall, decided I was going to take myself totally out of my comfort zone and and just see what happened. I matched to my top choice, which was a community mental health center so remote that it's removed from the nearest road system by over 500 miles. Flying is the only way to get here (it's literally almost Siberia - an hour's flight from the Chuckchi Peninsula). We also don't have reliable cell service or internet half the time. This move took me 4,000 miles from home and my husband wasn't able to come up here for over three months - talk about fear, anxiety, and plenty of moments where I was sure I had made a HUGE mistake. I got off the plane and didn't know where anything was, had no transportation, my phone didn't have service, and I was terrified. I also had a brief medical emergency within the first week which didn't help me settle in. Moral of the story is, though, I went through more personal and professional growth here than I could have fathomed. I don't even have words for it. It is a HARD training site but the idea that I was pushing myself to grow made me want to keep at it. I stayed here for my postdoc, just completed it last month. I would not change anything about this experience even though there were days (weeks, etc.) when I was super frustrated, overworked, and just tired.
Your postdoc may be something you are dreading but I can virtually guarantee you will get something out of it - even if it isn't what you thought. I would encourage you to try to take that mindset about it because it will make the experience a lot easier.