First I would like to say hello and welcome to COL
,
I'm sorry to hear your are experiencing problems with Laddy, I can only imagine how distressing it must be for you and your wife.
I'm not an expert with dog's that show aggression ( just a mum of 2 cocker's ) but I would say that I think you probably need some outside help with him. Quick!
He is at an age when dog's can show their authority ( especially males, but not always ) when they reach the teenage years, it normally starts around 8-9 ish months, what youv'e described does sound like an extreme version of this.
I would make an appointment with your vet, ask his for his help in the form of a behaviourist and talk to him about neutering, I would do this today.
It's possible this is a result of his breeding and his start in life, these are things that you will need to discuss with your vet.
Good luck and let us know how you get.
ps I'm sure that someone with more experience in this area will be along to give you more accurate info