No YOU should have not left your phone for her to look at in the first place and YOU should have responded "please show me some respect by not touching my phone. im not the one that has cheated you are..." if she turns it around on you then it might be time for YOU to tell her that "YOU have no reason to TRUST her right now and that if she wants to be in an OPEN MARRIAGE then she needs to MOVE OUT!!" Then tell her that she has until MC to decide. You are done with this....
