High social anxiety levels around my male coworker who is attractive but isn't nice

I am super shy and self-conscious around him, even though I'm not even sure whether I like him anymore because he's not very nice to me. I find him attractive but I don’t know him and I don’t even know whether he’s single. So far, I have kept my distance and minded my own business. The issue is that something about the way he acts makes it hard to forget him and I can't get him off my mind :(

When we were friendly, I only had about three conversations with him, but they were fun and lively. Until about three months ago we were on friendly terms, but then he kept on giving me mixed messages I could not make sense out of, and then I suddenly started receiving social cues that he wanted nothing to do with me, so I figured he didn’t want to be friends (maybe I was an unwanted distraction if he was in a relationship?), so I moved on and ignored him. Then I even avoided him by making some changes to my schedule. But then we still saw each other from time to time, so I just tried to go about my business and pretend he didn’t exist.

However, just when I began to start feeling better and forgetting about him, he started glancing and staring at me again, and then looking upset when he saw that I just looked tense and nervous (because the whole situation is awkward for me), as if I was being rude. The last time we interacted was in the kitchen when I was accidentally in his way when I didn’t need to be in that spot. He sort of barged in my personal space because I wasn’t paying attention that someone was behind me. I moved and said sorry and he said no problem, then I glanced at his face to see and gage whether I should make small talk with him just to ease tension, but he looked completely uncomfortable and nervous, so I left the scene and sort of scurried away as I brought back my cleaned dishes.

Since then, when I pass him in the hallways, if I even do so much as accidentally look at him, he glares in this angry, defensive, and somewhat hostile way. Then he often scurries away when he sees me, or if he has to walk past me, he’ll walk much faster as he’s passing by me. What did I do? He obviously has no desire to converse with me, so I think that my unsocial behavior makes perfect sense. When I acted nice and sweet to him months ago (while staying professional and acting normally, yet shy and awkward), he was at first very nice to me, would often glance and smile at me, and once we flirted. But he also gave me mixed messages (such as smiling and greeting me one day but purposely not returning my greeting the next day and acting agitated around me, making negative comments about me in the hallways, and many other inconsistent and off-putting behaviors), which became more and more frequent, and then, almost overnight, he suddenly acted like he wanted to avoid me at all costs. It's as if as soon as he "changed his mind" he wanted to erase my existence and deem me to be worthless as a human being. So I quickly stopped engaging with him, but apparently that irritates him too, so it's like my very presence on this earth bothers him, even though my behavior at work has been exemplary, and no one else has an issue with me.

I'll also add that this guy is otherwise very social and outgoing and everyone talks about how he is such a "sweet guy", when he is only nice when he wants to be, and he acts like he is annoyed by the presence of people who are different from him. I have social anxiety, OCD, and other anxiety disorders and it makes people like him think that I'm not worth socializing with or getting to know. Whatever his problem is, I am not going to revolve my entire work day around avoiding him, concealing myself behind my computer, being afraid of my own shadow, and hiding away as if I did something to be ashamed of, as if I was some sort of criminal, just because someone feels inconvenienced by me when I did absolutely nothing to them. This is now only his problem and not mine.

However, the most painful part of this situation is that when I sense this sort of negative judgement, it makes me long for his approval again, even if he doesn't intend this, so it's like having an old wound ripped open again and it makes it hard to get this off my mind.

If this guy has any remaining desire to socialize with me, or at least see my perspective, can't he understand that the reason why I have been cold and guarded around him is not because I didn't like him or rejected him, but because he wasn't nice to me? I'm so tired of being misread.