anyone who spits in the face of a woman needs to get help in the form of an intervention or a fist to the face. since the latter won't help too much in the long run, i'd say talk to this person (with other people to support you who also know whats going on if possible). the wife may have said don't say anything to him, but abused women make rationalizations.

good luck, sounds like a real shitty situation to know about/ deal with.