bf's Facebook password

ok so I just asked my bf for his facebokk password and automatically he was like "why do you want t for what?" but with like such a nervous tone in his voice and then I kept asking for it and he would like try to change the subject so when I asked him what he was doing he was like "oh just deleting all of these messages with some girls cause I know you're gonna get mad" so like wth and I told him I wouldn't get mad unless there's things like you know while we were dating and stuff or like talking talking! and he's just like asking me why I want it so bad and idk he's done some stuff where I've like lost trust in him and stuff and idk is it wrong of me for this ...?