Libby, Her father's passing was no excuse for rude/crude behavior. She was pissed that your car tax form was included in w/his and the fact that both are still in his name. Can I assume that she does not have the authority to open your h's mail? If not, that's tampering with mail and you will need to make sure to keep a copy of what she's done to the form as evidence, if there ever comes a time that you need to pull it out.
As for him and questions, continue being the person you are. If he wants to talk about it, listen and then advise him that the document was legal document for your state that she had scribbled on. Someone is now going to have to explain to the DMV as to why your form is a mess. I think he should be the one to take care of it since it's his nut case that did it.
Time is on your side and giving her plenty of rope will surely hang her.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
