A big part of her wanted to keep it all a secret from Antonin. She didn't want him to know everything that happened. It was too embarrassing. He would get angry when he found out the extent of her friendship with Rodolphus. She also knew that he deserved to know what was wrong with his wife. He'd been the second most affected person in all of it. It might have been Hermione's mind that was messed with, but he was right there with her for all of it.