I am so sorry for you. I know how badly this hurts. I've found my fair share of inappropriate messages. Whatever you do, do not let him know how you know, just quote things he said back to him. This way he can't deny that you know (honestly he might even deny it then, but whether he admits it or not he'll know you know). What's your next move? I mean after the confrontation? You need to know that anything he says at this point is going to probably be a lie. I really know just how you feel and I really feel bad for you. And by the way, denial is really really powerful! Don't let it trap you. Take care and get yourself together before doing anything. Honestly, I think you should kick him out. It's ballsy, but it might just scare the sh*t out of him. No matter what you do, just remember that you really can't control what he does. I've been learning that the hard way myself. Take care.