I'm sorry but I really don't see anything wrong with a man pleasuring himself in the middle of the night- even IF the wife's in bed, but that's just me....
This could go one of a few ways in my mind:
Make a big stink about it and have him deny, deny, deny & you'll never know what's really going in his head.
If you think he wants you to stay asleep, pretend to be sleeping and see what he does?
Then you can either
a) Jump around and scare the pants of him bellowing "SEE I TOLD YOU SO!"
(sorry that ones kinda funny)
b)wait for him to finsh and give him hell for jizzing on the bed or your back & tell him to "NEVER DO THAT AGAIN!"
c)let him do his thing and know he's not hurting anybody by pleasuring himself...
If you catch him doing it again, reach over and help him out a bit. NO!
With your hand or your mouth, help him get off.
When you've finished (or he's finished I guess you could say) turn to him and playfully ask, "So what was that all about anyways? You do realize you could have woken me up for a bit of fun- right?"
And LISTEN to what he has to say!!!
Honestly, some men have a fetish for women who are sleeping, maybe that's it? Maybe despite every thing he's done in the past, he still feels sexually interested in you and he's affraid you're gonna turn him away for his mistakes?
The only way you're gonna know is IF you take the time to ask him nicely. He's obviously not gonna just admit it- so catch him in act (preferably playfully as it will make more fun for him and yourself to roll around a bit before you get to the bottom of it all) and once he's 'relaxed' he\ll be much more receptive to chatting when he sees you know about it and you're OK with it.
he's denying it because you think it's dirty- take the stigma off it and you'll get an answer- GARENTEED!!!!!
Man is least himself when he talks in his own person. Give him a mask, and he will tell you the truth~Oscar Wilde
Ideologies separate us. Dreams and anguish bring us together~Eugene Ionesco
Once you chose hope anything is possible~ Christopher Reeves