From what I've been reading here it sounds like she isn't giving you much reason to trust her. She's cheated on you and doesn't want to tell the other guy that she's in a relationship with you. Even with every rule or boundary out there if you can't trust someone they're meaningless. If I were you I'd have her live by herself to see if she is just with you for someone to stay with and pay the bills. If she really does love you she'll still want to be with you even if you aren't living in the same place.
Everything will be ok in the end. If it's not ok it's not the end.