I just read back and found your post -- this is good Mom4K. I think that is very likely. HKS may have orchestrated it "accidentally on purpose" and made Anna think she was ultimately responsible. She may not have believed he would/could do it intentionally (which he may have), but in the end she felt it was HER drug addiction that caused his death. She certainly seemed to spiral downward after that.
The grief mixed with guilt must have been unbearable. And HKS used it to wield even more control over her, the finances etc...
The worry for HKS had to be what ANS would say at the upcoming inquest when pressured under questioning. I am sure HKS preferred that she not testify at all. And, maybe it was too much for her as well.
Thank you!, I thought it made sense.