Aitj for telling my brother the devil is going to get him after her kept messing with my dog

I have a 3 year old dog that I got right before Christmas, and I take care of her myself. My little brother is 7, and he plays with her a lot, but sometimes he’s way too rough and doesn’t understand that he can hurt her One day I saw him outside literally kicking her, and I got really mad and told him to stop and I also told our parents, and he got in trouble for it and talked aout it but even after that he kept picking on her and bothering her.

After a while I got really mad because I felt like nothing was working and he wasn’t taking it seriously. So

I told him that if he didn’t stop messing with her, the devil would come get him and send him to hell with other little boys who hurt dogs. After I said that, he finally stopped and hasn’t messed with her since, but now he’s saying he’s been having nightmares. I didn’t think I said that much at the time to cause him to have nightmares I just wanted him to leave my dog alone but now I feel kind of bad and I’m wondering if I went too far.