Thanks for your question. I am a solicitor in Scotland. Can you tell me why you are being sued for this money if it is your uncle that owes the money?
If your uncle gave you the money it was not a loan from her to you because she gave the money to your uncle. What he then does with it is nothing to do with her; her issue is with your uncle if at all and I think even then she would be hard pushed to make a case. You will have to defend this action as there is no legal basis for it as far as I can see. Happy to discuss further.