Is he cheating

You know him better than we do.

However, I will tell you that that's rather specific and well put-together and well-targeted spam -- and spam is not normally like that (you know how women end up getting erectile dysfunction spam? It's because the vast majority of spammer don't bother with the details and just send their crap to everyone).

I think it's time you had a talk with him. Even if he isn't cheating (personally, I classify that as close to porn), he's still not telling you the truth, and that's pretty troubling by itself.