How do i get over leaving someone on there own?

You did what was right for you and that is not a bad thing to do. Facebook is not the only way to contact this guy. You know what his timetable is - find a way to get in touch and say you feel bad about leaving him alone but you would love to stay in touch anyway and can you meet up some time? I think you have to make the first move here, but you have done nothing wrong.