Oh pesca, I'm so sorry that you made that decision in a moment of weakness and it has backfired so badly on you and your little family of 3. I did a similar thing; all the warning signs were there, my grandmother tried to talk me out of it, my ******* ex even missed the premature birth of my son because he was 'fishing'... And I named my son after him. So when he's in trouble, I have to remember in the heat of the moment to shout 'name-exe's surname-my surname' instead of 'name-ex's first name-ex's surname'.
I wish I could change it. But HE, who chooses to have ZERO contact, refuses. And my boy would always have to fill in the 'have you ever been known by another name' on forms... So next year, when its not childcare and centrelink crap, I'll be enrolling him in prep under the name I want him to have, which is legal. So there's ways around our mistakes!