Well, it's over with now! My sister just paid me back in full WITH INTEREST!. It was at a duration of time that she said that she would pay me back.
I went through lots of moments fantasizing on how mad I was going to be and that I would sue. So glad it didn't nearly come to that.
So now I'm free and have to decide where to put the money. I just couldn't wait to come on here and say it. Thank you to those who had comforted me.