Re: Penis Size
You ARE larger than any men in my experience and larger than average according to almost any reliable charts.
You, of course, should make sure that your wife is completely aroused and very well lubricated before penetration. Extra lubrication may help. But if she's been complaining that it hurts for EIGHTEEN YEARS, then for pete's sake, don't thrust hard in those positions!
Perhaps you can find a thick cock ring to put around the base of your penis as a stopper so you don't go in quite all the way when you thrust.