I'm sorry, is my boss a 70 year-old man, or a 15 year-old high school girl??

So I work in a "special" clinic, where we do things a little differently almost all the time, and most the time it pisses me off. It's all because of our civilian in charge. He was AD for over 20 years, and retired 26 years ago, and has been working in his position EVER SINCE. Man is old, and a pain in the ass. I CONSTANTLY butt heads with him. I am very direct and straight-forward, and when I have a problem with someone, I go to that person and hash it out, rather than behaving like a tween and going behind their back and talking to everyone else except them about the problem. This turd chooses to behave like a tween. At the age of 70. Today's issue: Today was not a normal clinic day, so I was going about admin duties and doing pre-deployment stuff, and my NCOIC was doin her thing. All of a sudden, Dude went walking through the clinic with 2 women, headed towards the waiting area. I didn't think too much of it because he randomly shows people the clinic sometimes and I thought this might have been one of these occasions. I was on the phone, but shortly after I hung up, one of the ladies came walking in to my office stating that she was told to check-in with me for her 10:30 appt with our doc. Needless to say, I was slightly confused being that we didn't have appointments today and I wasn't told anything about someone coming in. I asked Dude if he had cleared this with our doc, and he said he had and that we just needed to book her as a walk-in for the computer and he was ready to see her. I figured, alright, I'll do this, then address the issue that I didn't know this was happening later, because this is not the patient's fault, it's Dude's. Turns out it was more complicated because she wasn't in our system so she had to be registered but I don't have that access and my NCOIC was out at the moment. I went looking for someone who could do it, failed, headed back to my clinic, then just in time my NCOIC came back and was able to do it. I asked if she knew about anyone coming and she looked just as surprised as I did, so clearly she didn't know. So after we took care of the patient and she was gone, I went to Dude to speak with him. I have had problems with him in the past perceiving my directness as snippiness, or being disrespectful, when it's not the case at all. This time I purposefully took a neutral stance and explained calmly that it would have been nice to know that someone was coming in so that I could have been prepared, rather than having it sprung on me when I'm already in the middle of other things. I thought this was a reasonable request. He instead proceeds to give me dirty looks the entire time I'm talking to him, then makes the pitiful excuse that I was on the phone when the person called requesting to be seen, as if I would NEVER be off the phone again! I just reiterated that I would like to be kept in the loop, and in a clinic of 5 people, communication shouldn't be an issue. Everyone except the 2 techs knew what was happening, which seems like a problem to me. I could tell he was pissed, which pissed me off because all I did was came to him with a real issue, calmly expressed what had upset me, and left it at that. I had NO attitude, and no other issue with him at that point. I was at my desk working again when he came in and very aggressively questioned me on something I had said, and he had it wrong so I corrected him, informing him what I really said, then he grumped off. I'm just completely fed up at this point because I know he's going to grab my NCOIC when she gets back and immediately bitch to her about how terrible I was and whatnot. Before he could get the chance, as soon as she got back I told her what had happened, and our secretary confirmed my story. Sure enough, he called her in his office to talk to her, and basically threw me under the bus, saying I was standing with my hands on my hips, acting snotty and bitching and being rude. NONE OF THIS HAPPENED!! He made the whole damn thing up! Furthermore, I learned that he had bitched to our secretary about me already, saying the same thing, that I had attitude and stood with my hands on my hips. I cannot express enough how much this pisses me off. He is a grown ass man, going around talking to other people about his issue with me rather than talking to me directly, and making shit up that never happened!! I asked my NCOIC if she could negotiate a meeting with all of us where I could speak to him directly with her there as a mediator, and he obviously refused because he knew he was lying and he didn't want to look like an idiot in front of her. Plus he's a goddamned chicken shit. So anyway, nothing got resolved because he went home early (shocker) and won't be in tomorrow. Honestly, I don't know how I can speak to him without him taking it as an attack, even when I specifically try to be respectful and polite. He sees what he wants to and hears what he wants to and he gets what he wants because no one will stand up to him. I would, but it's just not worth it at this point. I have one more week left with the bastard, then I'm gone and hopefully he's no longer here when I get back from my deployment. He's dead to me! Fucking childish bullshit! Anyway, this was just a rant to get it off my chest and put out the type of shit I put up with on an almost daily basis. FUCK IT!!!