It's impossible for us to address all of the hypotheticals, but you are in a good position in that you have never been charged with wrongdoing, you believe that the police don't suspect you of wrongdoing, and people say a lot of things when they are trying to get out of serious criminal charges.

It sounds like she (or her attorney) wants you to play along - flee to Mexico, and let them try to blame you without you there to defend yourself. You are under no obligation to play along.