I am actually not feeling as hard on AW. She failed her son in every way, absolutely no doubt there, but I don't think her crying in court is necessarily wholly a performance.
Recently, she changed, and Logan changed. Initially she had a very close relationship with her mother and was visiting with Logan's father and Logan looked healthy. Then she tells Logan's father they can't visit anymore because JC doesn't think it's right, and can no longer have a relationship with her mother because JC doesn't like her, and Logan's appearance begins to change, losing weight and looking pale with dark eyes.
I think she was in a situation which was deteriorating so subtly she didn't recognise how bad it was, and she has a personality which is intense, dramatic, and reliant on a relationship with her current man (whomever that is at the time). I think her home-life 'normal' became what we know it to be, without her even recognising how wrong it was. Kind of like, the cobwebs and dust build up in my utility room and I think hmm I should deal with them, but I don't, and after a while I stop noticing them altogether. They just are. My sister will come round and say "Lucy, what the hey!! Look at this mess!" Like I would if I walked into her house and saw the same. But to me they've become an unnoticed part of the environment. I know that's a crude correlation to make, but it's how I imagine it.
So I think maybe her reaction in court is that of most humans. She'd possibly become blind to the severity and the frequency of the maltreatment of Logan because it had escalated subtly so the boundaries of what was normal punishment or rough play were only ever being marginally pushed further. But now, the details of how severe his injuries and how horrific his pain and suffering, is being told to her and illustrated in fact.
All MOO
ETA: Her being overheard shouting "What have you done with my son? Where's my son?" Leads me to think she wasn't fully involved. However, her shouting "You told me he was alive" makes it clear she knew his condition was critical.