How can i tell my friend to stop beinning such a jerk

1:whatever bạn do don't call them a jerk(that would just make them get defensive)
2:stay as calm as bạn can
3:make sure bạn and your friend are alone when bạn tell them
4:give them a example.like bạn say" yesterday at lunch bạn đã đưa ý kiến I was stupid and that hurt my feelings.It would be cool of bạn to not say mean things;can bạn do that for me?" that is just a example.
If your friend is not understanding then I wouldn't hangout with that person much.
I hope I helped:)

Like the person above đã đưa ý kiến - don't call your friend a "jerk". It'll just start the conversation off badly.

Maybe bạn could just tell her how bạn feel bởi how she's been acting. Don't be too straightforward. Be calm. Try not to make her get offended bởi bạn telling why bạn think she's being mean to whoever she's being a jerk to. This probably didn't help. :\

I agree with the trước đó two, do not call him a jerk. bạn could ask if everything is ok? Give some examples of what he's done and maybe mention it's not like them. That way it opens communication. There's a small chance that something is going on with him that bạn don't know about. He may be taking it out on bạn without knowing about it. But even if that's not the case, it will let him know in a nice way that bạn don't like the way bạn are being treated. Communication is the key to get to the truth. Good luck,