My boyfriend has his phone with him all the time

It's on him all the time 
It's always on silent 
He lays it face down to charge 
He faces it away from me when he's on social networks 
If I even check the time he gets angry, snatching it out of my hands.  
I cought him a couple times doing things on his phone that I didn't like. Like 
looking up naked woman.
Talking about me.
 Telling his friend who is a girl he misses her. When I confronted him he said it's "as a friend" 
he's lied to me several times over our relationship. I feel like I'm stupid sometimes for giving him lots of chances. He said he would never cheat but I don't know. Maybe it's all in my head? What do you guys think??