Just gut wrenching. I am so sorry for both your loss and hers.
I know all situations are different, and words are just words in screen, but my wife and I lost two children to premature deaths. She was absolutely devastated as you can imagine, right around 9-12 weeks if I remember.
Such a burden to bear that I wouldn't wish on my worst enemy. God always has a plan, as weird as that sounds.
As for the praying to the dead thing, I completely agree with you. Scripture says the dead know nothing (Eccl. 9:5-6) and we get into some dark spiritualism when we start making idols of dead relatives and such.
This is a crazy topic to dive into, but I'm right along with you in what the bible reads.