I don't know the full story either. I do agree with others. If you had a fear or concern at the time that someone committed a crime, then calling the police is a responsible step to take.
Then it's up to the police to figure out who is and who is not lying. Hopefully they will do their job and the justice system will figure out what the truth is. I realize this doesn't always happen, but that doesn't change that you are not to blame.
It is not justice or helpful to beat yourself up for calling the police and reporting information about a possible crime. That's called being a good grandmother.
If your granddaughter shared information about being abused and is now recanting her story, and that's why you feel she lied, slow down on thinking she lied. Victims recant all the time, especially minors.
If she absolutely did lie and made up abuse or crimes that didn't happen, that is morally wrong and horrible, and is a big cry for help. It is a pretty extreme act and sounds like she is going to need adults acting responsibly around her - and that's exactly what you did.
Try not to victim blame yourself if she did triangulate you, it ironically makes us more likely to fall into the triangle again.
Keep being the safe and responsible grandma that you are, one who takes the possibly of criminal behavior seriously, and don't take on blame that isn't yours to take on. :hug: