Gusto, sorry to hear the news. It sounds like you have accepted your fate and are already pro actively trying to situate your future. That said, I dissagree with everybody. If what you have is already bought and paid for, there is no sense in offloading it for pennies on the dollar. In the grand scheme of things selling one of the few things that makes you happy is just another let down. Remember, once this happens, money is gonna be tight. So even if you do change your mind and decide you want back on an ATV, it probably won't happen due to your financial alone. Not to mention the down time you will have when all this goes down. There will be times when you need to occupy your mind when there is nobody around to keep you positive. Wrenching on a bike is already an activity that you know you enjoy and you will still be able to enjoy. Just get a stool/seat on wheels and a decent bike lift and you are golden.
You would be surprised at the amount of people who competitively race and have some pretty extreme physical disabilities. I personally ice race with a guy who is paralyzed from the waist down and he is pretty quick. There are ways to set the machine up so that you can continue to enjoy it. When I shattered my left leg there was a possibility that they were gonna take it off from the knee down so one of the first things I did was start researching what/how guys are setting up bikes and Atv's for disabled riders. With the right parts you can do all the shifting from the bars, or even set up a prosthetic that can work with the shifter. If you can move what they leave behind you can make it work.
I honestly think you should try and make it work first. Because it will be healthy to have motivation and a reason to push your self. (Kids are motivation as well, but you need something for you as well) Worst case scenario, you try and make it work and it's to much. Then you can sell it. Just don't jump the gun and wish you hadn't.