Is dementia due to a UTI reversible?

This is the second time I've posted here in as many weeks, but I'm having another problem, unrelated to my mother's issues. These issues are with my dad. In October of 2014 he got a really strong UTI which took all his strength away, leaving him unable to walk or even stand up. Before then he had been fairly independent. He went to the hospital for six weeks and when he was discharged he was about as bad as he had been when he went in. I put him in a temporary, short term care rehab center, where he's been since December. Physically he is much, much better - so much so that I'll be able to finally take him home by the end of the month. But since he's been in rehab he's developed a great deal of delusions. I'm pretty sure it's due to the UTI, because he never showed any signs of dementia before. Among his delusions (which are very detailed and complex) are that someone broke into our house and stole all his musical instruments; he says I know who these people are and may even have been in on it myself; he says there was a press conference about it on the news and he keeps begging me to call the FBI. Also, he thinks I've dropped out of school, am doing drugs and have demolished the car. He also thinks my (nearly) 91 year old mother is having or was having an affair with his room mate at the rehab facility. Everyone tells me I should just humor him about all this, but I cannot stand him thinking these things about me and my mom. When I visit him I try to assure him that I'm still in school - I've even shown him my transcripts to prove it. Sometimes he believes me and we move on, sometimes he doesn't. Yesterday, for example, he kept warning me that cocaine possession is a felony and begs me to stop - he says he can "hear" me making drug deals outside his room every night. Anyone who knows me would understand how ridiculous this whole scenario is - I've never even done pot! In fact, my academic progress is going very well and there's even a (very good) chance that some of my work will be published in 2016. Before he got the UTI he was very proud of how I was doing in school - this is what I want him to know! I know it's the wrong thing to do (or so I've read) to contradict him, but I try to convince him that none of this stuff is true; sometimes I manage to do it, but he just returns to it the next time I talk to him.
Anyway, the point is I want my father back. Yet I know that this might not ever happen and that this may be the new normal. I'm hoping that when he comes home, that when he is in a more normal, familiar environment, sees that his instruments are still here, sees that I'm still going to school, and as the infection continues to clear up he'll be a bit more like his old self. But I wonder if I'm being naive. Is dementia due to a UTI reversible? Should I stop hoping for something that may never happen? Has anyone else experienced a loved one getting dementia from a UTI and recovering from it? And how do I handle his negative thoughts and worries about me and my mom? I'm not willing to agree with them and acknowledge them as being "true." But I don't want to make him feel like he's going crazy, either. Preparing myself, because I'll be dealing with it on a daily basis when he comes home.