Do NOT go on his page anymore, and as was said, focus your mind on boys who are more like you and might become interested in you. If need be, distract yourself with ANYTHING--reading, TV, movies, girlfriends, etc. Some people who get obsessed even do things like put a rubber band around their wrist and flick it so it stings when they start thinking about an inappropriate topic. You can get over this obsession and move on to someone more appropriate! And, of course, avoid him, as you are doing.