This is a difficult problem, that a lot of people face. Children can be the meanest people you meet. Here's my opinion.
I would be bluntly honest with the child. I would tell him that the things he says aren't nice, and that they hurt your feelings. Sometimes children can shirkshrug off an adult telling them just that they aren't being nice, because they herehear that any time they do anything bad, such as not sharing. They don't really care at that point if they are being nice or not, but he may understand having his feelings hurt. I don't think ignoring it will help him. It may help you, by making him stop eventually, but if your goal is to help him, let him know that it hurts your feelings.
On the other side, let him know when he does something you do like. If he's ever being really positive, and doing things you like, be sure to reward that by interacting with him more. I know that sounds like the alternative to that is ignoring him when he's being mean, but that doesn't work with all kids.
All you can do is be honest with him at this age. Hopefully, he's developed enough empathy for that to help. I hope it gets better. Good luck.
