Caroline, I fail to understand why, over the year in which he was planning this deed, she didn't confide in ANYONE, nor it seems, did she have any kind of conversation with him about his reasons for wanting to resort to such an extreme action.
We have been over this many times, but why, oh why, did she leave sleeping pills at Jeremy´s place when he alledgedly had talked about using such a drug on his family, then burn down the house? How could she have sighed with relief because she knew he had ditched his plans when he called her on the night of the murders and said, Tonight is the night, it is now or never.

(Makes no sense - at all - to understand that statement the way she claims.)
If we are to take her words at face value, she could have warned Jeremy´s family of the imminent danger and SAVED them.
I don´t GET this shite! There is no logic in her statements.
My only conclusion is: either she was in on the whole thing, even proactively providing sleeping pills and absolutely accessory to murder by not warning the victims, OR she made the whole thing up (to get back at Jeremy and/or to get herself out of a very tight legal spot concerning her criminal activity.)
In neither scenario she comes out smelling of roses, sorry Steve, she just doesn´t!