My stepson has been missing for 3 months Update

My husband has been struggling to keep his relationship with my stepson who was 14. We live Hawaii and he lived in Texas with his mom, stepdad, and half siblings. His mom has primary custody and my husband pays 1200 in child support. We have him summer and certain breaks. My husband has been trying to talk to him for a few months but his ex claimed he was mad at him and didn't want to talk to him. He gave his ex his new number for his son to have and his "son" did text him. Claiming he didn't like me and didn't like my kids which he seemed fine over the summer. He's supposed to have him this Christmas and he was ignoring him again so my husband told his ex he was going to take off work to fly down there and talk to him because she said he didn't want to come down here for Christmas. Well she called him and also told him not to tell that bitch (me) their business but she has no idea where his son is and he ran away 3 months ago. She never reported it to the police because she figured he would come back and she has 2 other kids to worry about. This also means she was collecting child support for a child she didn't currently have and never reported it. She said she was pretending to be him when texting my husband because the day he ran away she had taken his phone away after he got into it with his stepdad. My husband lost it and called her some choice words. So I'm having my mom watch the kids so we can fly down there and make a police report in their state because mom is refusing to because it's been too long and she doesn't want CPS questioning her and she has 2 other kids. My husband has been panicking because this also means he never got my husband's new number. What parent doesn't report their child missing for 3 months?

Update: We've been up all night. My husband didn't sleep at all. We have made a police report. The police is involved along with CPS because of his mom failing to report. She's now saying she knows she was wrong to not report but that my stepson is mentally ill and extremely manipulative and needs help so if and when he's found to not believe what he says. She was "crying" saying he's really mentally sick and cannot be trusted. I know I shouldn't have spoken up but I said that I know him. He's not like that when we were in the police station and she said she's his mom and carried him and she knows him. Now she's mad that CPS is going to be in her business and blaming us because she could potentially face a child neglect charge. She's a teacher so with a charge like that she could lose her job and has blamed us for possibly taking food out of her kids' mouths. But the police even said when a minor leaves you can wait an hour for them to come back but after you have to call. Not wait 3 months. My husband finally cried. I think everything sunk in.