This cat had been feral too. Sent me to the ER for a bite. But I persevered, and got him to cross the house threshold after a good year of enticing him closer. Once he, he refused to go out again for a long time. "No. I'm good" he would say when I left the door open for him.
Then I moved to a new village. He wanted out so bad I let him. Now he's in and out all day long. No more peeing inside.