I actually don't blame you for going through his texts. Sure, it's technically not the right thing to do, but I think a lot of people would do the same thing if they were in your position. It sounds like you don't trust him (going through texts/questioning his intentions/etc), and... I'm really, really sorry to say this, but I think it's understandable. He doesn't seem like a trustworthy guy - suggestive texts to his "mom," vague conversations about work, a girl kissing him on the cheek...
Personally, I wouldn't bring up the texts. He'll get offended that you went through his personal belongings and his trust for you will definitely waver. Just mention that perhaps you're feeling a little insecure -- he'll either reassure his feelings for you, or he'll make you realize that you deserve so much better.
Good luck! All the best!