I feel for you, I would hate to be in that position but luckily like Stuart and Laura, OH & I discuss all things together and both do the same.
Your OH clearly doesn't realise how tough he is making your job with Sam

Have you spoken to your OH about it all and explained how this is making your life tough?
All you can do is step up the training with Sam and like Claire says make your bond strong with him.....
I have to say I don't blame you for walking away when Joe bombs over to a leaded dog, I would too, it's just bad manners to allow your dog to behave in that way friendly or not!