I am not meaning to sound harsh here, but there is no gentle way to say this. If a child was sick and throwing up on the carpet, you wouldn't make them go live in the yard, right? So since you have recognized the fact that Rocky is doing this because of a medical issue, the only fair thing to do is to have his medical issues addressed so that he can be comfortable and able to live in the house again. Cats use inappropriate elimination to tell us that there is something wrong in their lives, since they cannot communicate with us in words. His peeing on the counter and on towels is his way of telling you that something is wrong with him health-wise that needs to be addressed, so the only fair thing to do is to take him to a vet and get him well again, not put him outside to face the elements by himself. From the sounds of it, this was not your decision, but your husband's, but still and all, if you are going to keep pets, seeing to their veterinary needs is part of the deal.
It would actually be kinder for you to locate a rescue group that will take Rocky in, treat his medical issues, and rehome him than it is to banish him to the outdoors after 10 years of being a housecat. It's definitely not safe for him out there, since his whole life he was indoors, away from vehicular traffic, away from predators like hawks, dogs, coyotes, and other wildlife that could harm him. Now, suddenly, he is left to face them with little or no experience on how to deal with them.
Please either take him to a vet and have him treated, or contact a rescue group that will take him and address his medical issues. Chances are, once you get his health restored, his litterbox habits will return to normal as well, since he managed to go 9 years without having litterbox problems. I am confused about one thing - above you wrote about his litterbox, "which was not cleaned everyday,but it was cleaned everyday". What does this mean? Was the box cleaned every day or was it not? Also, is Rocky neutered or is he intact?
If you would like help locating a rescue group, PM me. I am located in Texas as well, and I will do my best to help you find a group that will take Rocky. A 10 year old cat still has a lot of years left. Rocky deserves to be happy.
Ghilly
Trying to make an indoor an outdoor always involves a danger of "incidents" leading to kitty's health/death. You're right, he'll have to learn, as the price to failing in those lessons is often final and fatal.
Regardless, even the wiliest stray will have bad luck...it's just life.
i'm not clear on one thing; his peeing is a result of a health issue? If so, and the problem is treated, it's possible to have him relearn proper toilet etiquette.
If you are concerned you can lo-jack Rocky. At least you'll be able to find him should he go missing and get him the help he needs.