After carefully watching [verbal and non-verbal cues] and listening to this interview with the Spades I think that Kate, if she wasn't 187'd, was [somewhat] of a victim in all this.
She seems genuine, authentic, and absolutely loved motherhood. This 'mask' does counter to the occult symbolism found in her designs.
The fact that in her suicide note to her daughter she said [not verbatim] "It has nothing to do with you… Ask your father." speaks volumes to me.
Then we see him leaving with that mask, which is very symbolic.
Perhaps she, knowing and accepting her part in the 'cult', finally realised the depraved depth of it all.