Accidental Homewrecker??

I (21F) met this really nice guy from my university (20M) during the 1st week of school. We are on an exchange program in Japan and since I was here last semester I’ve been making an effort to meet the new students. I meet this guy (lets call him Luke) who I instantly feel a connection with. Things are going really well, we have the same sense of humor and a lot of interests in common so things are going very well. Luke and I end up going to a local bar I recommend, get pretty drunk, and end up hooking up at my dorm room. I’m very quick to catch feelings but I decide I need to get to know him more, so we go out for breakfast the next morning. Luke then drops the bomb he’s in a 4year relationship with his high school sweetheart. F*ck. What do I do? Am I a homewrecker?

I tell him that its not really my business and that he needs to be the one to tell his GF. He agrees but says he feels awful about what happened. I start feeling like shit because I really put this guy on a pedestal in my mind and hes treating me like a drunken mistake. Luke assures me he really does care about me and explains that his girlfriend had many previous partners while she has been his only serious girlfriend. (I understand the frustration but also why not just break up with her?). I told him he needs to chose between experiencing other people or being with his girlfriend. His exact words were “I don’t wanna explore a relationship with you.. but I do.” What the actual f*ck?? I look through Luke’s social media and find pictures of his girlfriend and start feeling miserable. I feel like the accomplice to a murder. Almost every post on her page is related to their relationship or him in general and I feel so awful. Luke and I still hang out frequently and I feel somewhat attached to him, but his girlfriend is still very important to him. All in all, I don’t know if I should feel guilty, sad, angry, or a combination of all three? Any advice or opinions are appreciated..