Omg, what a tragic way to lose your pet! I am just so sorry for your family especially, your poor Mom to have to mourn the loss of Heidi!
I don't know because I haven't experienced this yet...but, I know any loss is painful but, when it's unexpected & as tragic as this was I think your Mom's reactions are normal.
Because of the magnitude of discovering Heidi the way she did...I wouldn't be surprised if she is not having some kind of post traumatic stress-type reaction.
My heart just goes out to your Mom and please tell her I will keep her in my thoughts & prayers!
May sweet Heidi R.I.P. somewhere over the