Legal Question in Family Law in New Mexico

He should file a response to her Motion, stating his reasons for opposing the motion (basically what you just wrote). Go to the hearing and make his case to the judge. Be sure to meet the deadlines in the pleading he got. Hire an attorney if possible. There's no magic here, just keep opposing her and do what the court asks. He can find the form for responding to her motion at www.nmcourts.gov. He can also go to the courthouse and ask for the self-help desk to get forms.

Recognize that the courts generally prefer to keep the parents in a child's life to some extent, so he may have to accept some level of visitation at least. He can ask the court to limit it to supervised visitation if he is concerned for the safety of the child. She's not likely to get any form of custody if she cannot show that she can provide a safe home environment for the child. He should be prepared to testify to her failure to see the child for three years and to present evidence of her drug abuse or the other problems you cite. This could be personal observations by him or persons he would bring to testify as witnesses, police reports, court records.