I do not know about the family law side of getting a hearing but I will make another suggestion related to criminal matters. If the guy is on parole or probation, you can contact his parole or probation officer and express your concerns and the basis for the concerns. It is possible to make no contact a condition of probation or parole if the board or judge sees fit to do so. If the guy is on bond with a pending criminal charge of assault, then you can contact the prosecutor for the court and talk to the prosecutor about getting a no contact order made a condition of his bond.
To find out if he has a pending case or is on probation, check the county website and / or call the clerk's office. You will need his name and DOB. (You might be able to do it if you only have his name if it is an unusual name.) You might also be able to google it. To find out about parole, contact the local parole office with your concerns and they can check to see if he is on parole.
(If he has been convicted, is on probation, or is on bond for assaulting your ex, frankly he should have a no contact condition with her. If he is violating it - even if it is with her permission - then he can get any of those situations revoked & be incarcerated.)
In the meantime, hire a family lawyer ASAP to get the ball rolling in family court.
Although I have answered the question to try to help you, you should consult with a lawyer in your area in person on the matter. In addition, my answer does not establish an attorney-client relationship between us.
What? That's crazy. I do CPS in Harris County and they would at least investigate. I've got another idea. Check what the school knows. They and the police are top people to report CPS and CPS listens to them. Otherwise, record conversations with the mom stating what's going on - it's a little more than just having an email. I hope this helps. This is only guidance. I'd get a lawyer though because this is crazy.