I completely understand how deeply you feel these things, but I hope it empowers you a bit to know that I for one am 100% certain you absolutely can find love, have kids and get a job in your 40s.
You mentioned wanting to move back to the US, which could be a great medium/long term goal. If that feels like what you want, I'd consider setting this as a goal on the horizon and then working backwards from there to put together a realistic plan for how to achieve this. Otherwise, set a different med/long term goal like moving to some other location you prefer or maybe getting a certain type of job. Setting a clear goal and then planning towards it can have a remarkable impact on getting shit done. It doesn't need to be perfect. You can adjust your goal and your plan as you go. Take baby steps, and celebrate the small wins along the way.
Finally, since you have an engineering educational background, with remote work and online resources these days, my sense is that it would be so much easier than you feel to brush up your skills and start working again. The world is big and filled with quite a few CRUD apps! I don't have enough context to know what fits for you, but there are so many tutorials and online courses that walk you through practical exercises to build real stuff. Once you set a goal and put together a sketch of a plan, consider if it feels right to pick some online courses/tutorials and build some stuff to refresh your skills and give you some recent work to point employers/clients to. Some that I just happen to have seen lately: Buildspace (fun weekend coding projects), Replit has coding tutorials. I always like Michael Hartl's Rails Tutorial.
I hope some of this is helpful.
This present post is from the organization that discovered the issue and fought for the industry to recognize and study it. It includes a nice searchable database of test results on the bottom of the page.
Can you perhaps provide some sources to back your claim?
"the kidney is very adept at excreting excess sodium. But there’s one thing that inhibits sodium excretion by the kidney—insulin resistance. High insulin levels increase blood pressure, even with relatively low sodium intake. And many people are insulin resistant—and those people do need to lower their salt as a treatment of the disease."
Startup Owner's Manual by Steve Blank will show you the way: https://www.amazon.com/dp/1119690684/
Some plan for what to do in response would be…very helpful.