Your husband is going to turn you hen into a prize fighter, lol. The smaller hens are often on the bottom of the pecking order and will be the first target often in a gang attack. I have seen the vicious side of chickens, mostly due to unexpected or prolonged confinement. Mine actually killed a polish rooster by pecking his crest open. I believe it has to do with driving out members when territory is too small, but of course in confinement the one being attacked has no where to go, a switch get turned on and the taste for blood will drive it after the initial attacks. So whether protein or boredom is the cause it can be hard to tell, so I'm glad you will address both issues. I have choose to totally free rang my birds since and haven't had any behavioral problems since. The more room you give them the better they will be.
I like to compare chickens to people. If you were to be put in your bathroom with 5 other people and that was it, how long before you are trying to kill each other. Give you the whole house, add another ten people, you are a bit happier, but some still will have problems, give you your whole house and a yard, add a few more people, now your life is a little more tolerable. That's my analogy anyways, chickens get just as bored as us humans, they just can't tell us.
I would make a separation pen within your coop or run for the pecked one to get back to being part of the flock, but still where she can't be pecked for a while, sometimes issues can be worked out between a fence. Maybe your husband should exercise the bully hens and tire them out, make them do laps.