I guess my thoughts would be to speak up for yourself. Not responding might actually be feeding his criticism. It may sound twisted, but if you don't call him on his behavior, he may think you think it's fine and appropriate...which it is not. Granted, I understand "picking your battles", but when your soul starts to get crushed, it's time for a wake-up call for both of you.
For the first few years of our marriage, I used to just take it because I didn't want to be as bad as him in saying critical things. But it just ate away at me, getting me more depressed. It wasn't healthy for me and it wasn't healthy for our relationship. I had the sense to get help, even if he resisted it for years.
We've been married for 17 years now. Much of it has been great, some has been good, and parts of it have been downright rotten. But we both are invested in making it work. It took years to get him to go to counseling. And truth be told, the first adventure with counseling was a disaster. I was a screaming meemie and probably looked totally unreasonable to the woman who counseled us. But there was just too much pent up inside of me. We both decided ultimately that it wasn't working, but at least we got a few things off our chests.
Then a couple years later, we tried it again, aiming for family counseling as a whole. It was much more productive. It was with a male counselor and my husband actually did much of the talking once a comfort zone was reached. It was his first time ever in counseling and it actually helped him to see things differently. I had to stop myself from chiming in too much on occasion, because I realized my husband was actually opening up a bit and I wanted this phenomenon to sort of play itself out.
Later, we included our 11 y.o. son as well, because our behaviors were so interconnected and needed to be sorted out. It helped immensely for all of us. We had several boundary issues that had gotten in the way of healthy ways of relating as a family. Too much blame was flowing and not enough personal accountability...on all sides.
The key is to get counseling or have a very frank talk with your spouse. If your husband won't go, get counseling yourself. I did that for years until my counselor said she had done all she could unless the two of us would consider couples counseling. I had been afraid that would lead to divorce. But she said more often than not, it leads to better relationships rather than divorce. Regardless of the outcome, at least you can move toward a healthier direction on your own. If he at some point becomes involved in counseling as well, two points for him and for you as a couple!
I was close to considering divorce a couple of times, but realized that really wasn't what I wanted. What I wanted was to cultivate a better relationship. It required work on my part and on my spouse's part. It wasn't easy, and it's still not perfect, but it is MUCH better now than it had been.
All I can say is that 5-10 years were the toughest for us in our marriage. And as much as we love our son, having a child inevitably puts strain on your relationship. No one said marriage was going to be easy. Some of us make choices in spouses that are harder than others to deal with. The big question is...is it worth it or not to work on it? If you can honestly say yes, then go for it.
Talk to him frankly. Be honest with your true feelings with yourself and with him. Sometimes we can be amazingly dishonest with our own selves in an effort to smooth the rough spots.
I realized I was allowing behavior that I never would have accepted elsewhere. The reasons can be many and complex. Intelligence and education have nothing to do with it. I come from a family of many advanced degrees. But that doesn't always mean I always make wise choices and choose my words wisely. That being said, I have a lot of insight and wisdom that we tap into daily. (I don't want to sell myself short!) I suspect you do, too!
Why do you take the criticism from him and what does his criticism trigger in you? That might be a good starting point for your counseling and thinking. Add a couple tablespoons of frustration and anger, one cup each of fears and candid questions, and you might begin to make a yummy recipe for future communication.
You might find that the "recipe" isn't worth keeping. But you might find wonderful nuances to your relationship that never existed till you risked being honest with yourself and your spouse. What do you have to lose? Just remember you are worth fighting for, and move forward from there. It certainly sounds like SOMEthing has to change at home for you!
P.S. Beware of the hormone monster. Make sure you are attending to your health and wellness in all of this. And enjoy your new little one when he or she arrives!