I don't think you can just pretend you never read that and act like all's well.
Doing that will put everything else she says/does in question.
Do approach it cautiously, even with an apology for looking at her texts but just letting her know how hurt you feel. If you come off accusatory in any way, she'll get defensive and focus on you reading her texts. If you share how hurt you are in an "I feel" kind of way, you'll probably fare much better.
Just don't make any references to Jovan Belcher during the conversation.
"Chiefs fans arenít having it." -Jason Whitlock