I did, and I don't regret it. Ex was a poor husband, but he was a good father to the kids. Also, he was in the defence force so if we'd separated while the kids were young, they'd have seen very little of him.
I made the decision to stay until the kids were grown, and it worked out well. Ex and I lived like brother and sister, but we never showed any animosity in front of the kids. I left when they were 18 and 22 - dd was engaged and had left home already, and ds was in an apprenticeship. Ex stayed in the house and I bought myself a flat a short distance away. Ex was out of the forces by then of course.
The kids were upset when it happened, but they had their own lives and friends. The upset was more along the lines of needing to know that ex and I were ok.
It's been 15 years now and I'm happily remarried, ex has a long term partner. Kids both married and we have 5 grandchildren. I rarely see ex, but my DH and I see the kids every week.
I occasionally talk to the kids about the separation - it's not a secret that I stayed with ex so there would be a stable home. The kids have said that they had the best life growing up, and that they were grateful to have that stability.
It might not suit everyone, but if the parents can get along and give the children a good life, it can be a good option. I know that MN says it's a bad idea, but every situation is different. You make your own decision.