Grief is exhausting, Dennett, a special sort of exhausting while it's so raw and there is so much to deal with. Sometimes you just have to leave stuff undone and sit.

I've never shopped at Walmarts (never even seen one in real life). That behaviour was appalling. I'm sure reporting it would help in some way but I'm also sure that's way too much hassle for you to think about at the moment. Of course, you could do a short social media post along the lines of "Why I will never shop at @WalmartOrg again" and provide a friend link to this post.