If you don't mind a religious curriculum, I recommend Rod and Staff.
We moved so much during my childhood, and the schools never taught the same math concepts, so I have huge gaps in my math education. I was very nervous about homeschooling because of math.
I studied about different theories in math education, and decided that I needed a "mastery" curriculum with plenty of practice and drills.
I chose Rod and Staff arithmetic. With each year package, you get a teacher's manual that is amazing, a student book, and extra drills and practice sheets. From third grade up, the books are all nonconsumable so you can use them for all your children.
I recommend that you start with first grade, yourself! Read the teacher's manual for each lesson, because it thoroughly explains the concepts and gives examples. It literally gives a script for the teacher to say to the student, so the manual can "teach" you in that way. Then do the lesson, do the practice sheets, do the flash cards or whatever is assigned, grade your papers, and the next day, do the next lesson.
Then when you go to teach first grade math to your child, you will totally know and understand how to do it. While your child is in first grade, you can study the second grade book.
If you are not able to do that, then study the lesson the night before your child does it. That is what I had to do when my oldest was in fifth grade. Apparently I never learned fifth grade math. I studied the lesson and did the problems, and if I got stuck I asked my husband to teach me how to do it. That was with a different curriculum; with Rod and Staff I can understand it on my own.
I am passionate about math education, especially in homeschooling. Did you know that the United States is not really succeeding at teaching math in the schools? I've read so much recently about teachers not being able to pass the elementary math tests. I am not pointing fingers, here, because I wasn't properly taught math, either. I'm just saying that I think it is good to identify the problem and figure out how to do better with our children.
If we choose to homeschool, then it is responsible to tackle this lack. I appreciate your willingness to do this! It is hard. I used to feel so silly (and stupid) studying a fourth grade math book when I was over thirty years old. I think many people wouldn't, especially if they can do the things I can do, such as balancing a checkbook, ordering things out of a catalog, etc.
But I agreed with you that if we want our children to really understand and really be good at math, we need to try to learn it ourselves.
I am now doing sixth grade math. When ds moves to algebra, I plan to buy Teaching Textbooks and let the guy on the DVD teach him. I'll do the lessons along with ds at that point.
I do know many homeschool moms who use Math U See and do the lessons along with their kids. I prefer Rod and Staff, but Math U See has a great reputation, too.