I don't know enough about Aaron to call him on his bullshit, but as someone who was in this world a decade+ ago (drugs/booze, not swinging, sober now), every story Aaron has told is completely believable and Nick sounds like a proto-typical cokehead. The Web-MDing everything that Aaron spoke about is spot on, they will always have a reason and 'completely logical' explanation that, if only you were on their mental playing field, you'd understand.
He talks about how the kids weren't aware - if Nick and Kayla were blowing up that frequently with company over, I can't imagine what that household was like when they were alone. I bet the kids would be too afraid to push any subject with them or then be the outlet for their aggression. I'm speculating here, but it tracks imo.