Phone Dilemma

My husband and I ordered new phones and he received his new one first while I will get mine within a week.
Since my phone stopped working completely, he suggested that I will use his older phone until I will get my new one.

I never look at his phone all the years and he never looked at mine. And yet when I set up my Whatsapp on his phone, I suddenly saw all the chats that he had, as they were saved on the device itself. I was also able to see that all his regular text messages and photo gallery are still there.

When I was about to send a text message to my brother, it showed me the last message that my husband sent him few months ago, asking him to participate in giving money for a gift, and specifically asking him not to tell me.

What I realized is that I have two choices before me: I can practice self-control and choose deliberately not to go through all his chats and respect his privacy, or I can choose to look and risk finding out things a wife might rather not find out.

My brain is telling me: ‘Well, if you found out that message he sent to your brother, who knows what other skeletons are in there, perhaps even flirting with other women, you should check it out.’

And it seems like a way to protect myself, to check if there is something there, and yet there is the other part of me that says, ‘What good will it do to check and maybe find out that he did flirt with someone or lied about another thing?’

As a fairly new scholar I wonder how would you suggest to deal with the dilemma of looking vs. not looking.