OP, I'm sorry you're going through this.
Your boyfriend sounds terrible. It's one thing to not like your significant other's hair, but it's another thing to say something that hurtful. It was unnecessarily cruel and I would question his role in your life if you're planning on keeping him around.
It's time to visibly show that you are not approving of these comments. I had to completely stop any kind of laughing or playing when comments like these came up to nip it in the bud. Don't look downtrodden when they say these things either. Look proud and keep your head up.
I noticed once I started exuding more confidence about my hair, people started keeping their mouths shut more. The ones who still opened their mouths to spew garbage got off my back once I started to spurn them openly when they started that nonsense.
You can get through this and believe me, I know it's hard. I agree that you should try to find some naturals off line. Even if you have nothing else in common, it's still a great conversation starter when talking about hair
Good luck and feel free to vent, we're listening!