There's postpartum, and then there's "I think about hurting myself", and then there's "I think about hurting my kids".
1 means "get therapy, ASAP", 2 means "24-hr supervision, either by a family member or in an institution", and 3 is "only supervised access to the children, period, until further notice".
I think the story a tragedy, I hope that there is a LOT learned from it so that maybe future tragedies can be averted, and I'm not gonna chime in on either side for this specific case because I don't have enough information.