In Texas, there is a Cause of Action for defamation. Because she has falsely accused you of committing a criminal act, you may sue her for Slander Per Se. If you can show how her lies have damaged your reputation, caused injured feelings, or caused mental anguish, then you may be entitled to general damages. If you can show that she has actually caused you some form of loss (loss of employment opportunity, loss of earning capacity, loss of past and future income) then you may be entitled to special damages.
However, since she is an ex-wife, and I presume that you two may have children, this may be something that you desire to bring up in an action to modify child-support or custody. Speak to your attorney to find out if this is in your best interest.
As far as "charges" I presume that you mean "criminal charges." If it arises to the level of harassment, then you may be able to file a police report, but likely your remedy will remain in Civil law.
You may want to try and send a Cease and Desist Letter, to see if that will bring an end to her antics. Hire an attorney for the letter, as one from you will have no affect. If that doesn't work, follow Mr. Harris' advice.
Sign up to receive a 3-part series of useful information and advice about personal injury law.