I'm not familiar with Ca law, but I'd think it would be easier now that he's disappeared. You proceed as if it's a default decree, leaving everything at status quo, which is how you wanted it, right? I mean, if he wanted or needed ongoing support, he'd be there and open about showing his records and tax returns. If he's not around, it means he doesn't much need your support.
Let me make a guess at what happened that made the extreme litigation happen a few months ago... he shows up at a lawyer's office, gives half the story, hears that he may be able to get support from you and gives authorization to go after you with everything they can muster up... The laweyr gears up the war machine and goes at it. The more they find out, the worse it looks for their client. They yell at him for not telling them everything that was relevant to the situation, and tell him that he's not as likely to get anything unless he starts showing proof of what he has been claiming to them... They tell him to get moving on fixing his tax situation asap so they'll have something to show your lawyer to prove he's on the up & up... and in the meantime he'd better start paying for some of the excessive litigation that he got the ball rolling on. He disappears and their bill goes unpaid.
What to do in this situation? Drag them into court on intermediate hearings ... like motions to compel him giving up his IRS documents and bank records to prove how he's been financing his lifestyle in the past 3 years... and when he fails to appear, ask the judge for a judgment in default in your favor since he's not pursuing the case... which there's probably a procedure in Ca civil law that allows lawsuits to be dismissed or judged in the petitioner's favor based upon the other side not showing up, and all you have to do is follow that procedure. something like providing notice and giving him time to show up and contest it...
Ask your lawyer, there's probably a way to get this to happen.