You need to repost your question with more detail. Your question has no context and it is impossible to address all of the possible scenarios that may be implicated in your question. Are you in the middle of a modification for custody? Is there a parenting plan or visitation schedule? With whom do the children live? Do you have shared legal custody? Do you have shared physical custody?
As for very general advice - I would suggest that if your ex-wife alleges child abuse she has the burden of proof and will have to produce evidence to support the allegation. You may offer a defense (rebut her allegations and discredit her evidence), but it is difficult to prove a negative – ie, that you do not abuse the children.
While it sounds like you have some strong defense evidence (text messages, no physician report, no 51A investigation, history of mental illness), the fact that she has the support of her mental healthcare providers is unsettling. You may want to motion for a Guardian ad litem (GAL) who can provide an objective third party investigative report. Regrettably, GALs are expensive an the courts are rreluctant to appoint a GAL if the parents can’t afford one.
Since custody battles can be highly contentious and complex as experts enter the action, you would be well advised to confer with a domestic relations attorney.
This is not legal advice and is not intended to create an attorney-client relationship. You should speak to an attorney for further information.
Your question requires an in-depth analysis by an attorney in order to determine your options. Do you have joint legal custody of your children? Has your parenting time been suspended by the court? If you wish to obtain custody or preserve your parenting time with the children, it is imperative that you consult with an attorney.
DISCLAIMER: The information contained herein, and the receipt or transmission of same does not constitute or create an attorney-client relationship and the information provided does not constitute full analysis of any specific matter.