Why did friend's daughter send me nasty text?

Perhaps the message wasn't meant for you at all. The daughter could have made a mistake and sent it to you in error. That happens.

what was the text?

I have so many questions. What did the text refer to? How would your friend's daughter know about anything about you to create a nasty text with? How did you find out it was your friend's daughter? Why didn't you ask your friend, or the daughter, why she said what she said?

ask your friend

There is absolutely no way we can know this answer. Since you found out that the text did not come from your friend, but her daughter sent it from the friend's phone, then that was a good time to ask your friend why that nasty text was sent in the first place. Since you never met the daughter, any information the daughter has on you came directly from your friend. So, if there is personal information or an attack on something that is real, then your friend is a blabbermouth.

Could the text been sent to you by mistake? You have known this friend for 26 years and NEVER met her daughter? How odd.

Why not call your friend and ask HER what is going on or ask her to find out why her daughter did that.

Have a conversation with your long time friend and see what she may be able to tell you. Ultimately, perhaps suggest you have a face to face conversation with her daughter, with your friend as a third party so you can work through any issues that may exist unbeknown to you and and your friend.

Charitable explanation: She hit the wrong button when she sent the message. It was probably meant for someone else. Let it go.

She may have sent it to you by mistake. Have you asked?

cause shes mean, thats why