My cousins said I’m forgetful and get annoyed when they have to repeat stuff again. Is he rude for not telling me?

I have two little cousins that are so adorable but I keep forgetting their names. I was like, “I’m sorry I keep forgetting their names. What are their names again?”
He was like, “I’m not telling you because you’re just going to forget again. Hahahaha”
I was like, “Just tell me.”
He’s like, “NO! I an NOT telling you again. I’ve told you MANY TIMES. What’s the point? You’re just going to forget again. That’s what you do best. Just go over there and forget.”
I don’t know if he was just joking but it hurt me. My brother said, “Well you shouldn’t have asked. He shouldn’t have to keep telling you. Plus it’s annoying having to repeat the same answers over and over again. I don’t blame him.”
I said, “Just forget it!” They didn’t respond.
How rude!