Honestly, I know that these people kick up big feelings. I get it.
But you're projecting here and TBH you're looking for control over the situation that you're never going to get.
She sent a plant without a message. You said she never puts a message. So what's the point in getting so upset about it? She still won't add a message, and you've wasted time being upset.
You said you are angry that she didn't bring presents to your house. But you don't like her anyway, and she's never going to have a normal relationship with your kids because she's not normal and look on the bright side. She didn't come to your house. Bonus.
Her emptiness is her problem, don't make it yours by wasting time and thoughts on it. You can't fix it nor should you try. Stop asking why she doesn't do things the way you think they should be done. It's honestly not worth trying to figure out.
You can't make these people be normal, but you don't have to let them use of so much of your time and energy either.