I think you've left it too late to now move out to the wilds and try to have a self-sufficient life. A lot of people who have lived that lifestyle start moving back into villages or towns towards their late 60s and early 70s because even though you don't want to think about aging, you are aging and things start becoming impractical. You might end up needing to attend GP and hospital appointments more regularly, and no, you can't just get an air ambulance for that. You might find that you aren't able to drive any more for medical reasons. You might find it harder to drive distances even if you are still able to. You will find things harder such as digging in the garden and so on.
So I do think you need to let go of that dream because it's not going to happen.
However, I can sense your frustration with your husband. You're 67 and you want to be doing "something" but you are trapped and you don't know how long this will go on for because he shows no sign of retiring.
So that means you have to make changes now so that you get to enjoy your retirement years, not just sitting around waiting for him to maybe give up work at some point and your life can start.
What's your fitness like? Do you go out and hike in the countryside? I'd start with that.
If you want some inspiration, read "Grandma Gatewood's Walk" who hiked the Appalachian trail for the first time at the age of 67, or read the Wikipedia article on her which summarizes it.
There is nothing stopping you doing something like that (unless you have mobility issues of course).
You don't have to walk as far as that, you could start with hikes locally and then maybe do some multi-day hikes staying in guesthouses and then work up to multi-day hikes with a tent and go wild camping.
I am someone who wants to be out in the wilds but it's just not practical. I can quell this desire to run away from it all to a farm in the back of beyond by going on a long-distance trek every single year for at least a month, with tent. It's marvellous. The rest of the year I'll go and camp out somewhere overnight. It really recharges me. The peace in the evening and the wonderful morning light.
Also have a look at Andrew Terrill (google to find his website) He's someone who wanted to get away as a young person, out into the wilds, and ended up hiking 7000 miles. He then found it difficult to return to a normal life but he's found ways of combining that and having a family and a job and getting out into the wilds regularly.
I've also got a friend who is now over 60. A few years ago he was in a terrible state. His marriage had fallen apart, he had a new partner but then that didn't work out either and he ended up drinking and suicidal. He'd always been interested in the outdoors and with a bit of encouragement from me he started going out a bit more. Then he bought a camper van and started going up to Scotland every week. Things progressed from there and now he travels regularly in the camper van, parks up somewhere and goes hiking or climbing. He's found a balance between the "normal" life he lives in a city and the outdoors he craves while still being around for family members who need him.
I think there is a way forward for you OP, but think creatively about alternatives so that you can make the most of the years ahead.