He has my password but he is hiding something??

So my bf has access to my phone. Meaning everything on it. I'm very open and honest with him. So one day my charger was acting up and making my phone buzz a lot so he snooped through my email and found an email from a dating app I used to have. (I don't have his password or any access to anything of his)

So he is letting me use his iPad and he went on and deleted his history and logged out of his email. (I thought that weird cause didn't he just go through mine thinking something was here?)

So then I go on and look at the recent apps on the iPad and I see an email that must've just been what he was looking at before he logged out and it was clearly talking about me and how I have a problem with my weight. Or maybe it was how I don't like how his ex is skinnier than me (it bothers me)

Anyways. What I saw was a response, not his email.

The sentence said "she's obsessed with her weight and her hair, that part made me laugh"

That's all I saw and then my mind started racing. I never had asked for his stuff. And now I feel like he's hiding something from me. I don't know if I can trust him.