Hey man - Have so many feelings and thoughts in reading this. First, I'm sorry you're suffering. As an obviously articulate and educated person who is in reality fairly young, I'm 100% confident you have so much more potential than you're giving yourself credit for. Also, as you can see from all these responses, there's more compassion and empathy out there than it might feel like. It's ok to reach out to people for help. It's great that you took this step. I hope all these replies can serve as positive motivation/momentum for you!
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.
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.