Hmm. I wonder if his ex was right. I'd certainly want to know what those messages were all about. Of course he'd accuse you of snooping because you got into his phone messages. But when a woman suspects her husband of cheating, she's usually right, so I don't blame you for snooping into his phone messages. I'm sure he doesn't have a GOOD excuse for those messages. There isn't a GOOD excuse for them.
Talk to him about it. Then suggest that you two go to marriage counseling. It sounds like you need it. (well, HE needs it) I wish you the very best. Let us know how things turn out. God bless and take care. Hugs, Lee