The problem is that we've got a prisoner's dilemma going on here. Barb and Chris are now separate and may very well have opposing interests.
I think Chris will either lawyer up and be told to STFU or he might spill his guts entirely today with no coherent strategy.
Barb's best move for herself might be to act incompetent and feign that she has no idea what's going on and doesn't remember anything (alternatively, this may be true). That exculpates her from any charges (if it works) but if the prosecution can convince a court that Chris sexed up a demented old woman who couldn't consent... that's not just the incest charge.
Barb could say it's all bullshit, there was no sexual contact. That might be the best for both of them but if it can be proven false (say if Chris confesses to the police, forensic evidence, other electronic evidence, etc), both can be convicted. I think this is unlikely as I doubt they would have charged Chris so fast if she was both competent and denying everything.
She could also flat out admit that there was sex and she was fine with it, I guess. That would keep it to the incest charge but they'd both risk eating it. Maybe she figures no one is going to punish her with anything serious. Maybe right.
Barb could, at the end of the spectrum, completely throw Chris under the bus and say she didn't want it but he kept touching her (edit: this may also be true). This would probably work for her since even his own statements seem to indicate she told him to stop at times. I guess she could then TRY to help him play the autism card under Virginia law.
So the question is, how much is Barb willing to risk to protect Chris, especially given that we can assume their co-dependent relationship is not going to be allowed to continue? And whether she can even intelligently make these decisions anymore.
This going to sound REALLY cruel, but Barb may have to throw Chris under the bus.
If she implies that she was aware of what's going on and allowed it to continue, she could be facing a Class 5 Felony herself. And if the both of them go to jail, even if only for a year, they won't have a home to go back to. The bank would easily seize on the opportunity (and the subsequent lack of payments) and take everything.
If she plays incompetent (or is actually incompetent, make your own jokes here,) she would at least be deemed an innocent victim and allowed to return home. Unfortunately, unless Chris put her in charge of collecting tugboat, Chris' absence would mean a drop in household earnings, and that household can't take anymore financial worries as it is. On a side note: that house is also dangerous, and as laughable as it sounds, Chris not being there means that an old woman is navigating through a cluttered dwelling that's also a huge fire hazard. I fear that unless a caretaker is issued or she gets put into a home, that her life would be in constant danger to the point where it's not only a matter of 'if' something falls on Barb and traps her, but 'when.'
On the topic of Chris defending himself in court: Man, would that be a sight to see. But believe it or not, such a thing might actually
help him, if only for the reason that it'll definitely prove that he's crazy enough to be put into a mental institution as opposed to a prison. Unfortunately, if Chris does lawyer up, it's going to be a State-issued one. No Rob Bell to save his ass this time. Chris is at least autistic enough to read some rehearsed dialogue, but it'll all go to shit once the recordings get submitted as evidence, upon which, he'll end up spilling everything and sing like a canary or attempt to commit perjury in court.
The question of what Barb is willing to risk depends entirely on her mental state and how much she actually cares about Chris, or, conversely, how useful she thinks he is anymore.
There's a saying that goes that "All mothers love their sons," but if Barb was an manipulative as many people say, she may weigh these factors out to see which is more favorable for her, rather than Chris. And I ain't gonna blame her, I mean, after all, Chris DID rape her.