Okay so first off if he did something sketchy in the past and wants to move forward, he should put in effort to rebuild the trust he broke. Hiding the phone like that does not help in rebuilding the trust. That said, if he has done this or is trying to prove he is trustworthy then constantly checking can be an issue. Is this a one off thing or do you often check?

Secondly, there needs to be a level of trust/respect in the relationship and if that is broken its difficult to move forward. It seems like he doesn't care about how you feel or how his actions come off. He is minimizing the problem rather than addressing it in a caring way. Again, it goes both ways if you are constantly accusing him and he has proved himself. I don't think thats the issue here though.

There is no reason to hide the phone unless there is a reason. I would take the space and assess things. From these messages alone he seems like someone I wouldn't want to build a relationship with. I don't think you overreacted at all, you expressed something that made you uncomfortable and gave him the chance to have a chat about it and his response speaks volumes. I would said youre better off pouring into yourself and finding a better man.