Not sure if this makes me a scumbag wife or really smart

Smart.

Definetly smart.

smart, no question. unless of course you use the money to run some sort of cartel.

Hiding important stuff like finances from each other never ends well (I've done it myself and once someone thinks the other is capable of lying the trust is gone it's a relationship killer). I'm crappy with the finances and my wife took over that part of our lives - I took over the stuff that she was crappy at. It totally took the load off me because that's her area of responsibility now and I've taken the load off her for my areas. This way feels like we're working as a team rather than one person having to be "the responsible adult" for the other one.

While it may be technically financially smart, your husband will feel deceived and like you don't trust him if he finds out

My ex did something like that.
Just another entry in a long list of reasons why she's an ex.

Saving is smart. Dishonesty will always hurt a relationship. Communication is key.

Just do what I do and say I'M saving but don't disclose amounts.

I had to do that with my ex. He found out and spent it. :(