I hate adults so much

Hello everyone! I wanted to vent a little bit about this situation, so i'm going to post it on here.

Me and my boyfriend have been together for 5 months now, and my birthday was last week. He got me a promise ring to celebrate and I love it and him so much. This morning, I had volleyball practice, but I didn't play because I need to take my graduation pictures today and I didn't want to ruin my hair (it's curly...). 

I was showing some of the girls on my team the promise ring because I wanted to wear it for my picture today. Then my coach came and asked me about it because he was curious and I told him you got it for my birthday from my boyfriend. He looked at me shocked a little bit then he asked me why my boyfriend got it for me. And I explained that the promise ring is a way to show that you're serious about a relationship and the occasion was just for my birthday. Then he started asking the other girls (who have been with their boyfriends for a year or more) if their boyfriends got them a ring, and they all said no. Then he asked me, "so since you have a ring and they don't, your relationship is more serious than theirs?"

I was so confused by his comment and I was extremely offended that he went out of his way to compare me to everyone else, and ask me something like that. And he was rubbing it in because he knew that they were together longer than we have been. And he said "well I don't believe in promise rings" and I just said "I understand". I was so pissed off. He had no right to say that, and he literally got cheated on with his last girlfriend who is a teacher at this school, and SHE went for another teacher at this school and they have two kids. Don't project your weak relationship life onto me just because you can't hold onto your own.

He's extremely unprofessional, everyone at this school knows that, so I just ignored him. Projecting that onto someone younger than you is so disgusting but I just shut up. The girls were being so kind and supportive too, they were calling us cute and commenting how you picked a really nice ring. And he just came and ruined my entire mood.

Am I overreacting or was he out of line?