Sorry this is so long, it's a lot to explain lol.
I live in an international share house in Japan and everyone is friends, but I became good friends with one of the guys. We would hang out a lot and I thought of him like an older brother because he always did nice things like cooking for me randomly. Well it became pretty obvious that he liked me, and I think it made the other house mates uncomfortable because they made nervous jokes about it a lot. I never expected him to act on it though, because I though it was obvious that it would make the house house situation awkward if two residents were dating. I like him too but I didn't say anything because I don't want to go out with someone n the same share house. Also he is slightly shorter than me without shoes, and I don't want to date a guy who is shorter.
The day before I left for my home country on a one month vacation, we went to the zoo and were joking around like usual when he said, "You know, I really like you. Would you be my girlfriend?" I was shocked and just said, "Ummm..." and shook my head no with a sad look. I could have given more explanation, but I would have had to figure out how to say it since there is a language barrier, and I just wanted to drop the subject as quickly as possible. Then he just said, "Yeah, I know." like he expected me to say no. Then for the rest of the night we just joked around like usual and acted like nothing had happened. That was one week ago and now I've been back in my home country feeling horrible about the situation. I feel like I may have been leading him on that whole time and then I just said "no" with no other explanation. Since he said, "I know" he probably thinks I am too good for him or something. But I feel bad if he thinks that because he is such a good person and is not bad looking at all.
SO my real question is whether I should send a facebook message saying I am sorry about not explaining more last week and telling him that he is one of the nicest person I know. I don't want to tell him the truth about why I rejected him-- because he's shorter and we live in the same share house, because I think that would just make him feel worse. I am thinking of just saying that I already like someone else, because I think that would be easier to take. OR should I just not send any message at all and just leave it be? I feel guilty now but bringing up the issue again might just make things much more awkward when I go back. I want to steer clear of typical lines like "let's be friends" and "you deserve someone great", but that is essentially what I'd like to say. But I don't want to send any message if it's not going to help at all. What should I do?