Problem with friend--don't know what to do

Hey there!This will be a long post, so apologies in advance. I just need some advice regarding a troubling issue with a friend because I'm so stressed out about it and how it's going to affect my semester.Some background: I'm a gay male in my late 20s, my friend is a straight-identified married man in his early 30s. We both started a grad program in fall of '14--we're co-workers at our school and classmates.A few weeks into the semester, I'm making copies at a copy machine, and I look up to see the guy just standing by the door to the stairwell staring at me. I wave, he scrunches up his face, and dashes through. The next day, he comes over to my office. The second I look up, he turns on his heel and leaves. A couple weeks into the semester, I notice he's staring at me during class. Sometimes long stares, sometimes he steals quick glances and looks away. He starts chatting me up more, and begins visiting my office every day. He usually has a question, which turns into a conversation, but one of my co-workers notices he's asked the same question multiple times. He starts acknowledging me in class: when he has to give a presentation I'm the person he calls on, he jokes about wrestling me, etc. He usually sits across from me--I wonder if it's because it's easier to stare--but on occasions when he has to sit next to me he fidgets and seems nervous. The staring continues outside of class--at events, parties, etc. During a guest speaker, he sat on a bench in front of me with a friend, and the friend kept trying to get my attention. Afterward, she said it was because he kept turning around to look at me. Another friend asked what was up between us, because when we were all waiting for our trains together, she said he was the only one who didn't say goodbye to me but he "peered around the column four times to watch you as you left--like a seventh grader with a crush." Friends have said he talks about me all the time when I'm not around. One friend even said that whenever the subject changed, he related everything back to me somehow. Like if they were talking about soup, he'd say, "Oh, that's __'s favorite kind" or if they were talking about a movie, he'd say, "_____ hasn't said whether he's seen it yet." We stayed together during a conference last year. First, he offered his coat for me to wear so I wouldn't get cold. Then, whenever we were sitting in our beds before sleeping I kept noticing him glancing at me out of the corner of my eye. When I woke up, he was smiling and staring at me from his bed. When we sit next to each other at the pub, he'll put his arm across the back of my chair and sometimes he'll turn towards me, put his arm across the back of my chair and put his feet up on the rungs beneath it. He often talks to me about LGBTQ issues and sexuality. Once a friend who also works in our office suite sent me a text that said, "Did I just hear him say 'homoeroticism' to you?"He'll also make cryptic comments about marriage and his drinking all the time. For our first semester, he didn't bring his wife anywhere. Many people didn't even know he was married. He kept talking about divorce, saying things like "People get divorced" or "Yeah, we plan on kids, but we know divorce is real, too." He downplays his marriage, saying, "We got married so we could travel." He has a tattoo with a vehicle named after his wife, and whenever anyone asks about it, he always jokes that it doesn't have her name on it, so if they get divorced, he gets to keep it (I've heard this "joke" like three or four times now). For a long time, when drinking, he'd tell the young singles in our program not to get married too soon. After the Christmas party our first semester (to which he didn't bring his wife), when people started to file out, he said, "Anyone want to go out for drinks?" A friend said, "Sure, but where?" He said, right as I was standing there, "I know a good gay bar but I feel like we'd need a gay guy to go there." (I was the only openly gay guy in attendance/in the program). I was angry that he didn't have the guts to ask me, so I left, but apparently he went out with a friend or two, got really drunk, mentioned getting married young, having "so much curiosity" (several times), etc. He got in trouble with his wife that night for not bringing her anywhere and has since brought her, which makes me feel terribly awkward because I have no idea what's going on with him.He wrote a story about a couple in a failing marriage who go on vacation to the same place he went on his honeymoon. A cloud-gazing scene from his story was taken verbatim from a conversation he and his wife actually had (he had told me about this conversation before, so when I saw it in the story I was like, "What?"). Near the end of the story, the wife finds out her husband had an affair with his co-worker when they traveled together (he and I were about to travel together for a school conference, the co-worker in the story had the same color hair as me, the co-worker had a very similar name to me, the only difference is she was a woman in the story).Other people in our program have remarked about his weirdness with his wife. They are usually extremely physically distant, with her being the only one to show affection. He's always got a drink in his hands whenever they're out together (he's mentioned getting drunk when she goes to bed or when she's away--she travels for a living). One friend remarked that they're "sexless" because they have no detectable chemistry.All this to say I don't know what to do. At the beginning of the fall semester, after not seeing him all summer, his hands were on my shoulders within five minutes of seeing me (he doesn't touch anyone else). The staring was still happening. He was coming to my office in his undershirt and telling me to look at things on his laptop (which he held at crotch-level). All this behavior read strange and by the end of the semester I couldn't handle it anymore. I arranged at talk with him before winter break in which I shared my concerns. He denied everything--said he doesn't have drinking issues, doesn't have marital issues, didn't realize he was staring or behaving weirdly, etc. He even tried to turn all this on me by saying maybe I was projecting. I countered by asking him why other friends have pointed out his bizarre behaviors as well if I was projecting, to which he said that was a fair point.I guess my question is how to proceed. I feel really hurt, because this is someone I see all the time who in all other senses has been a close friend. But it feels like he's been exploitative of our friendship and that he's comfortable dumping all his weirdness/issues on me. It's dredging up all this pain I was already feeling--I have virtually no LGBTQ community at school, so there's no one really to rely on here, and being around my straight friends means being around him. I've also really struggled with feeling lonely/isolated/painfully single, and now I'm fielding off intense attention from someone who doesn't even identify as gay. Couldn't it have been someone openly gay? I've just dealt with one problem related to my sexuality after another, but I haven't enjoyed a loving relationship with another man, and I'm surrounded by straight people who are constantly moving in and out of relationships, who have all sorts of privilege, and who seem to actually be experiencing life while I'm stuck in neutral. And they just don't understand my discomfort. Grad school should be enough for me without this guy adding to my mess. I think I'd have felt more comfortable just dropping him and avoiding him altogether if our program weren't so tiny that I have practically all my classes with him, we have to work together and we share a lot of the same friends, but it is and I do have to see him all the time.Should I be worried about this guy? Am I completely delusional? It's hard for me to believe that all of these weird things for the last year and a half were just some weird coincidence/misunderstanding, especially when other people noticed some of these behaviors.