Great, honest post. I've had these same revelations since starting parenting 5 years ago (I now have three sons - 5, 3 and 1). I remember getting pregnant with our first and thinking of everything as "how OUR lives will change" as we go on this great parenting adventure. And sure, beyond a doubt, my DHs life has changed with kids. He is super-responsible now, does a lot around the house to keep the "machine" humming, gets very little sleep right along with me, takes a kid or two with him just about everywhere he goes on the weekend, etc. But, my life? Wow - couldn't be more different. In many ways I am so glad for the change (what did I DO with all my time before kids??) because I love them with every ounce of myself and I wouldn't want to miss any of it. But, I definitely didn't realize before kids how much a woman's life changes when she has kids....especially women who SAH. I am so defined now as a mom. And, yes, the "home management" stuff can be overwhelming sometimes, especially since the more kids you have, the more juggling/lists/planning is needed.
For me, I've decided to just throw myself into it, embrace the change. Because I don't want to fight it and struggle - I DO love staying at home with my kids and I wouldn't change it.
So this is my life now and I will love it and cherish it because it will be gone one day. These kids with their incessant questions and needs will one day be independent and not need me as much and I'll miss it. And when that happens, I'll get back to relaxing in my free time, pursuing a career, etc.
As for how anyone has a second child? Well, I got pregnant with my 2nd when my 1st was 11 months old...so in some ways I just dove in. With each passing stage, though, I see that the whole "this too shall pass" mantra is true. The rough stages don't last forever and they are followed by wonderful, joyous stages.