Can someone sue me for eyelash extensions after three weeks ?

So I did someone’s eyelashes on the 4th of October and it all went well. Two days ago all of a sudden that lady calls me up and talks so rudely to me saying that I did a horrible job and then she gave the phone to another lady who claimed to be an eyelash artist. She was like you’ve ruined her eyelashes and that now there’s swelling because of me. I couldn’t believe it because I’ve been doing it for so many people and I’ve got a very very good client base and this would’ve been the first time this happened to anyone. She went on to call me and then my mom and threaten me to pay her the full amount. I agreed to give her half the amount because obviously the product is involved and it’s not cheap at all. But I don’t know what to do. She’s been threatening me ever since . She’s telling me to send the money to her boyfriend’s account and he’s been threatening my mom as well. What do you think I should do. So with eyelash extensions you usually have to complain within a week or it doesn’t hold any importance. Also she got someone else to remove it in the first place so if that procedure was done in a bad manner I have no responsibility there. Now there’s also this huge eyelash extension specialists forum on Facebook where I posted what exactly has been happening And literally 400 people ( eyelash extensionists ) have commented and said to not refund and just complain that these people are harassing me instead.