This person is threatening to sue me, should I be worried?

I've been telling people that a friend of mine stole an ipad from his grandmother to use as collateral to get a loan (which he didn't pay back)

and this is true…
I've been telling people this; spreading the word. Only because e he's guilty as charged and deserves to have his reputation ruined. (he constantly bothers people for money and he's a scumbag for doing that.)

his sister threatens to sue me for defamation of character.

she thinks I have nothing in writing.

a few things she isn't aware of:

1. Everything is in writing. It doesn't have to be a physical piece of paper; electronic communications are all saved, recorded, documented. Phone messaging, online chats, it's all there.

2. She has to prove these statements are false; which she can't.

3. She has to prove there are damages, which there are none.

4. It costs a lot just to file a lawsuit; I don't think those losers are going to pay the filing fee.

5. She doesn't even know where I live. It's very hard to sue someone with an unknown address.

Should I be worried?

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