I took it from her no-big-deal to be no-big-deal.
I am confused by her two re-actions, no-big-deal/big invasion of privacy.
The first reaction was her public reaction after being publicly embarrassed. In front of a table full of people, she laughed it off. That is
grace. To take you to task in front of them all, would have both of you looking bad. I am grateful she spared you both that kind of scene. It would have created more embarrassment, for her, you, and for everyone who had to witness it. Her feelings of embarrassment and violation were none of the table's business, any more than her mono was.
The second reaction is her telling you honestly what she did not like and how she truly felt. I hope you can see the value in DIL letting you know she doesn't want you to discuss her with other people. It beats her seething in anger and it coming out in other ways. It also beats simply avoiding you. If DIL didn't care about the relationship, she wouldn't give you feedback on how to improve it.
I hate that feeling of walking on eggshells. I'm not sure what her issues with you are when you talk
to her. But it shouldn't feel like walking on eggshells not to talk
about her. It can be quite easy - just don't talk about her to others.