I'm surprised there has not been many posts for dating over 40. Its hard when there is kids and not everyone will side up as allies. All you can do is teach your kids proper christian values. If they are her kids, christian values can be taught under your roof per se, though they may not get such at the ex's place. Part of the downfall of divorces. Anyways, the only control you have is what goes goes when under your roof. Maybe you can find a compromise with your ex on the christian values issue, but if its her kids and her ex, the only leeway is what you and your girlfriend have under your or her roof. Its just not possible to make any ex comply if they choose not too. Its their roof in that case and unfortunately you have no say or influence for what goes on there. You can only set the example under showing the kids the better way. Also these kids are growing up and will also decide for themselves what to believe and act ultimately, especially if they are teenagers. Younger children are easier to teach and are more receptive to the gospel even.
As for myself I raised my son on my own, since he was 3, now 21. I have only started looking the past recent while but the pond is very slim,especially for christians. Churches don't go out of their way to help singles find suitors in their church communities, and yet they don't want one becoming unequally yoked to a non-believer, but what choice is really left for the seeker of a mate?
Also by one's 40's a lot of suitors have children that have grown up and left home. that's the kind of scenerio I seem to be running into as of late.