Why don't you at least talk to some people about possible nursing jobs
and see what they have to say? It doesn't hurt to see what your options are. For example, you might find that your old employer would welcome you back and that you would get some of your seniority back if you worked for them -- meaning that you might not have to work all that many nights. Perhaps working a few night shifts would be a small price to pay for have "real" time off.
You also might be able to find a job that is not that of a bedside staff nurse. For example, maybe you could work for a hospital's telephone help line ... or in nursing recruitment ... or in risk management ... or some such thing. You have solid clinical experience, night supervisor experience, plus all the experience from your 2nd career. Who knows what type of job you might be able to get. It's not like you are a new grad and would have to start at the bottom all over again. Also, you have the advantage of not being in a huge rush to get a job. You could keep your old job for income while you explore your options and wait for something attractive to become available. You're not desparate enough to have to settle for just anything you could get.
You can afford to look a little before making any committments. So why not look a little? See what you find ... then make your decisions. Don't feel you have to decide now, before you have all the inforamtion on what your options might be.
Yes, your priorites might well be changing at this time of your life. You are older and wiser -- and probably a lot more tired than you used to be. You've lived more of life and learned a few lessons along the way. There's nothing wrong with that. That's the way it should be.
I'm 52 and thinking a lot about similar issues in my career these days. I have a "dream job" with a good paycheck -- but I am tired. It's getting harder and harder to cope with the demands of my leadership position and I sometimes long for a "nice little job" with a limited scope of responsibility and limited hours. As you said, our priorities change as we get older. The trick is to find positions that build on our extensive experience and knowledge that fit those new priorities. Fortunately for you are not having to make a hurried decision. You can take the time to carefully plan your move.