Who do you mean by “the School”? Can you clarify the situation for me, please? If it is the Principal, Director or a member of the Board who is accusing you, you need to request an interview immediately. Do so in writing and request, also in writing, that whatever ‘evidence’ “the School” has collected, be presented to you at the interview and in writing. You have the right to confront your accuser and you have the right to know what the ‘evidence’ is that the accuser is basing his/her accusations on. This is called Due Process.
If the acts you are accused of can be reported to the police, I would certainly suggest that you seek legal counsel immediately. My understanding is that jail in Mexico is not a pleasant experience. If the acts you are alleged to have committed are without foundation, I would certainly check into the possibility of suing the school and/or your accuser in the school for defamation of character. A lawyer can assist you in this regard.
If I were you, I would not simply let a situation like this drop, particularly if I were not guilty of the acts I was being accused of. Even if the situation never reaches the ears of the police, you may be tarnished in International teaching because, believe it or not, the world of international schools is a small one.