You make some good points.
There are perhaps a couple of missing pieces to my story.
On my part: I was married once, gave my all to it, and it turned out to be a terrible, terrible experience. I swore I would never give another person that much power over my feelings again.
On his part, he is from a rather conservative religious background which embraces the idea that a wife is always a nagging bitch. She lives up to the part. Because of the stigma within his community for himself and his children should the marriage end, he will never leave.
Were we people with different kinds of baggage, then either I would say forget it or he would get divorced, but as it is, the arrangement serves both of our needs. We both get companionship, support, sex, and a best friend without me losing my freedom or him losing his standing among friends and relatives.
If he took another mistress, I would be furious.
Essentially, I am his emotional wife while his "wife" is the business partner with whom he provides structure and care for his young children.
My only child, by the way, is a young adult and fully aware of the situation. The two of them get along quite well. He taught her how to drive, and she often works for him when he needs extra help at his office.
It is a crazy world we live in.
Thanks for the thoughts, I confess I was very impressed with your response. Indeed, life is complicated! But this helped me to see another side of things, so again, was appreciated.