@Abow84 put fraud alerts on all credit bureaus as well. It's another layer of added protection.
Update when his scores come in.
I'm not familiar with Cricket's setup, but I used to work in selling mobile phones myself with ATT/VZW/Sprint (when it wasn't part of T-Mobile yet), and whenever someone bought phones, there was no HP/new account ever reported (unless of course you default), so I'm not sure I understand how a phone purchase ended up on a credit report?
OP, I'm not in the camp of allowing or excusing toxic and/or illegal behavior because someone is "family" or familial adjacent. In fact, abusers often bank on the close/personal nature as a sure fire way to get away with said behavior leaving the aggrieved to face the consequences. This sad excuse has gone on for generations and needs to stop.
With that being said, if the mother of your spouse's children doesn't want law enforcement involved, then don't commit actions that yield such consequences. Don't set a dangerous precedent here, you don't want to encourage such illegal mistreatment in the future. I mean what incentive is there if she knows all you will do is look the other way?
Hopefully, you make the situation right for you and your spouse. You sound like you have enough on your plate, and there is no reason to let someone hinder your progress and hard work while they sew all the benefits at you and your spouse's expense.