You sound like a strong, resilient, sensible woman.
You’ve had a shock with this news and I daresay it’s re-triggered the past trauma generated by this abusive man.
This news has materially nothing to do with you so you can simply continue as you were if you choose to do so. As you rightly say, the “new wife” is not your responsibility and neither is it your responsibility to uphold the law for your husband. Not your circus, not your monkeys. I mean yes, in another scenario you may choose to speak up, but you are understandably fearful of this man so absolutely I understand why you want to have as little to do with this as possible. And why should you eh? It’s his problem.
By the way, I know others have said this, but you can certainly in the UK (and I hope same in Ireland) change your name to your maiden name whenever you like, even whilst married, as that is the name on your birth certificate and has always been rightfully yours should you choose to adopt it (many these days never change it, do they?).
Anyway, to return to my original point: it sounds like you’ve had an understandable massive shock and have been re-triggered, so can you give yourself some peace, reassurance, and calm? Re-establish your feeling of safety and security?
Keep shining on - you do sound incredible.