There is no such thing as a part-time mother and having kids in daycare doesn't mean someone else is raising your kids. My baby will be in daycare 3-4 days a week from 10months. This is best for our family both financially and for my sanity. I'd prefer 3 days but work will likely only agree to 4.
I enjoy my job, I'm good at it, I worked hard to get where I am and it pays well. No way can I just throw that away to be a SAHM - it's just not for me.
I don't think it will be easy and no doubt there will be moments of guilt (from things like that thread!) but I know it's the best thing for our family.
No point in justifying anything to others. People always think that what they are doing is the ideal/the best thing.