A good dog is a great idea. Plus, dogs that have been rescued from shelters really appreciate it. They don't forget it...ever. Is it possible to go back and get that one dog you saw at an adoption event? You seemed to really like her. We had a shepherd/dane mix we rescued.
He would protect us to the death. And he was HUGE. Sweetest dog in the world, unless you had a gun on you. Then, he would attack. My sister had a group of friends come over once, he lunged at one of the kids, I grabbed him, and a gun fell out of the guy's pocket!
I told him he had 2 seconds to get out or I was letting the dog go. He never came back.
I was looking for a large shepherd when I found him. I looked all over the pound, kept going back to him, but he never looked up, never made eye contact. He was depressed.
I told the guy I was taking him, he tried to talk me out of it, said he was old and they were coming to put him to sleep in a minute. I insisted. Even when they opened the cage he didn't lift his head. I knelt down outside the cage and asked him if he wanted to go and he looked at me, got up, and put his head on my shoulder. We had that dog for over 13 years! He was about 40 pounds underweight, had demodectic mange, and stank to high heaven. A month later, he looked great. 3 months later, he looked like a different dog.
I think you should tell your DH. After you have taken care of the security issues (dog/gun/whatever). You don't want the secret between you. You can't live like that when you are separated, you know? Trust is all you have. Can you tell my DH works out of town a lot? LOL! My suggestion? Go find a dog. A big one. Tell DH about the new family member, and casually mention that things have been a little creepy since he's been gone, and you decided to get a "real dog" like he's been suggesting.
Good Luck!
Shelly