He watches porn to learn 'new tricks,' but...?

On the one hand, you do need to be able to tell him what you want. On the other hand, if what you want is celibacy, then you should see your doctor and determine whether anything can be done to get your sex drive back if him cutting some of the kinkier stuff from the repertoire doesn't do the trick. There has to be a healthy compromise here...and if there isn't, then you'll either need to bring in a counselor or get used to using the porn as an outlet if you want the marriage to stay healthy.