I don't know TS but I know her kind. IMO she likely wasn't "mean" to Gannon over the years. She was worse. Syrupy, volatile, head-spinning but not identifiably mean. Not identifiable by Gannon. Because it was covert. Insipid.
Darling young man was a people pleaser... and what TS probably did was CONFUSE HIM TO NO END. Gaslighter. Lay blame on Gannon for imaginary infractions. Coerce him into apologies for things he knew he did not do. Just a guess, but I can imagine that AS never found ANY of Gannon's behavior unacceptable or not normative. But when he was AWAY, I bet he got an earful (of nonsense), both how great and motherly TS was AND how dreadfully disobedient Gannon was. Which he wasn't. Easily I could imagine how likewise easily TS could manipulate AS into thinking Gannon saved his best naughtiness for when AS was gone. All concocted and exaggerated and overblown by TS. "You don't know how hard it is to be a stepmother." Whatever. Because actually I do. And if you love a man who brings children to a relationship, you rise to the occasion, and take a sidecar stance, supporting him as he raises his children. In any case, equal to the final damage she inflicted on Gannon's precious body, I am as alarmed, disgusted and heartbroken for the mental confusion she fed him.
Even at the end. You are going to be in trouble for the thing you made me do.
I suspect she's spending her jail time creating speeches, certain she can talk her way out of this. Because woodworking tools. Because flower boxes.
There's something extra revolting in knowing that she likely still doesn't think she's done anything wrong. In her mind, all this happened TO HER. Twisted fother mucker.
MassGuy is right-- it's not the monsters that hide under our beds we should fear. It's the ones we invite right through the front door.
Tragedy heaped upon tragedy.
JMO