Do men change?

So I'm not trying to change him I just want him to be a healthier individual. My fiance is addicted to henti/amine/ and video games. The henti is all over his fb feed. He watches vidoes on video games as much as he can. Even games he doesn't play. He checks his fb immediately every time we stop the car. He is on second life and its all sexual roleplay of the anime variety...there is more to that but that's all I want to say.

He says its nothing but its something to me, I don't trust him and it hurts. He supposably got rid of second life and lying he got rid of it before.

Many may ha saw we recently just got our own place. But were not fully moved in and I'm scared to move in now. Can I trust him?

Constructive advise is much appreciated.

I know he has a problem and I want to help, but how long till I say enough?