Your post is full of irony OP. You accuse your DH of being unsymathetic, Aspergers like (excuse me if that wasn't you), but you're not seeing how he might view you as holding him back. You have a problem, he has provided a solution - not just an engineer's thing to do but a male response in general.
Likewise, you are presumably afforded to be a SAHM because of his job. Now, I get annoyed from time to time because my DH's work seems to consider it way more important than any work a woman might do, and I earn more money than him. But I also see the benefits he brings, as an engineer. He is practical, he is a hard worker, he is reliable - he could be so much worse.
You say you hoped your DH would change once you had children. Maybe he hopes you could be more flexible. 3 nights away isn't nice, but its doable - I know people whose partners work offshore for a month or more. But tbh you don't sound compatible, and he at least seems to be trying to find solutions.
As for the operation, I wonder whether you are afraid of this more than you are letting on. It does sound daunting. That said, if it offers a good chance of fixing the problem, I'd take it. If you pass up every opportunity, every chance for change, in your life, will it make you happier? Or not?
As for the medical treatment only being offered now. Are you absolutely certain that this isn't simply due to the change of job and a different scheme with different benefits?