I'm sorry this happened to you! Thank goodness your wife was ok and you got home so soon!
My puppy joined a household with 2 adult cats, no problem. The cats quickly made it clear to him that they were in charge, and he behaved appropriately.
He barks like mad when someone comes near the apartment, and I always tell him "good boy" and "thank you, that's enough" when I've checked the situation. (there are some hairy ones here in the apartment complex) He knows it is his job to bark. I feel much better knowing my dog is on the alert when I'm gone and when I'm asleep. I don't think he would stop an intruder, but he would certainly make enough noise to wake me or get the neighbors curious.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson