Wow. Given your ex's history, it wouldn't surprise me if this is some kind of tactic...like maybe he thinks this will garner him some kind of protection with regard to his "rights" or he will be viewed more sympathetically by the courts if he's going through this major transition. Maybe he thinks his addiction problem will be given a pass or overlooked.
Maybe it's real. Dunno. He's still going to be a person with some severe mental health issues and a drug addiction, man or woman.
Regardless, the only thing that matters here is how it affects your daughter. Have you been able to communicate with her counselor? Because this is another huge change for your daughter to process.
We have an expression in my house, which is a quote from Dorothy Parker...whenever we hear a text or email come in...or the phone rings, one of us intones, "oh what fresh hell is this?"
Kinda works in your world these days, yes?
Sending you a hug.