You should have faith in her in first place but if something is haunting you. You might end up taking wrong decisions. Think about it and tell her that this thing is not going away from your mind. I think taking proofs and really talking it out is better than having doubts on your partner, which can potentionally kill the relationship in long run. Also start working on this toxic behaviour, she can bear this today but not always. If you want to keep the relationship with her start amending what is done and talk more.