What's the big deal? You're not having sex, so go ahead and masturbate all you want. You don't have to tell her you are. That's your business. If she asks you, then tell her that you only talk about your sex life to the person you actually have sex with.
It's not a big deal.
That is something you should watch out for though personally. While most women have a healthy sex life, once they have kids and the hormones kick in, their sex drive goes down. And it's going to be real easy for you to get resentful about it. You're going to start off by saying that "you understand" etc. But when those dry periods go for a long stretch of time, you're going to find a different way or person to get your needs met.
And BTW, you do understand that the reason the two of you were having regular sex was because you were in the honeymoon phase. That ALWAYS wears off.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.