Carve out for yourself a "man cave" where you can be as tidy as you want. Bring your kids to see your man cave every now and then so they see there is another way of living. Leave her be.
Who knows what pregnancies have done to her hormones to push her hoarder's subconscious to the surface? Pregnancies are very big deals that leave long lasting effects on the body and mind. Give it time, maybe lots of time, for the hormonal levels to revert. After the kids grow up to the point where the kids spend more time away from home, she may want to go back to work and that may again change her domestic behaviors and tendencies.
Oh, after you get this off your chest and collected the advice, delete this thread before she sees it. In the old days these would be things you tell a few of your confidants who would exercise discretion rather than posting on the open Internet where it's readily searchable by your wife and her confidants.