What should I do about him?

So there's this guy that I think likes or used to like me. I couldn't tell if he liked me or just being weird he would say stuff like how loves my pants and pinch my clothing specifically my pants on my thigh and I told him that me and my friends are going to take pictures with this character we liked and he said how you would feel if I showed up in a costume and took pictures with you. He asked me, " Do you like it when guys make the first move and I said Either way works cause I'm kind of standoffish. I don't really know if this qualifies as someone liking me. His demeanor changed, when he found out I was single. Soon, he got his friend involved and started talking to me to clarify that his friend is gay and has a boyfriend. I had no clue who this guy was but he already knew me before I knew him. They would talk about me, I figured that out later, his friend had similar interests to mine, so I guess he was using his friend to "gain information" cause he would just ask about everything that I liked and then tell the guy I had a crush on later or what I said. Anyway, I tried to shoot my shot, and I'm very awkward, so I like drawing pictures cause that's what I have a bachelor's in is illustration, and so I drew him a picture of himself in a show that he likes. To give more context, this has been going on for like a month and a half, if not almost two. At the time of this, he wasn't seeing anyone, and I kind of waited a long time just cuz I was nervous, and then I handed him the picture and showed it to him, and he really liked it, but he started treating me a little differently, which I was confused about. He told me he was seeing somebody. I felt a little embarrassed and stupid, but I just treated him like normal cause I'm not going to get sad over that. Anytime he would mention him dating someone, he got really quiet and upset, and I don't really know why, even though I didn't bring it up or anything, and now he wants to hang out, assuming he wants to be friends?

What should I do about him?
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