I'm in 6th grade, but I have a crush on a 7th grader?

I'm friends with his sister and his cousin, because they are in the same cl as me. His sister and cousin tell me a lot about him, like what does he do, who are his friends, who did/is dating, you get the idea, right? So far they said that he dated 4 girls in his cl, but his ALWAYS hangs out with his recent ex-girlfriend, which is also one of his best friends (That's what the girl posted on her facebook profile) and I'm starting to get nervous about making friends with him because him and his ex-girlfriend always hang out together. His cousin told me that they broke up, but maybe they got back together? My crush knows my name, but he barely even notices that I'm there. And we ALWAYS p by each other in-between cles. This year, he held the door for me, and he said, "Ladies first." but one of my clmates walked between us, and then my crush said, "I was talking to Rosie!" I felt myself starting to blush so I ran inside the room, and I think it looked like I was ignoring him, and I really regret that! :( What can I do to make him like me?