Personally, I say, bring on her family. However, if you want to try something different (or in addition) to this you can always follow the way of the Greeks. In Greek mythology if you mistreated your wife, the harpies would come for you. Basically, they were REALLY angry women/monsters who were interested, mostly, in punishing men who treated women the way your barbarian is treating your elf. Usually, the harpies did thier best to rip you apart. If you want to get a sample of harpies at work, check out the Orestia (you can probably find an online copy)...they make their appearance towards the end of the Euminades.
Anyway, I know there are harpies in the monster manual, but for the life of me, I can't remember how D&D portrays them, and I don't have my books on hand. But if you want to take the D&D harpy and make it similar to the Greek version, just give them a general hatred of all things male, and a particular distaste for violence in regards to woman. I'm also sure they wouldn't be willing to overlook his friends who stood by and did nothing.
Your barbarian will learn the true meaning of the phrase "queen of the harpies" and, hopefully, will come to his senses. If not....well.....have fun designing her mother/father/siblings etc....'cause I'm sure they'll be looking to bring a world of hurt to this guy!
T from Three Haligonians
Edit: Oops, it was late last night when I wrote this...replace harpies for furies, but same idea.