You will achieve the opposite. You and the stbx will be growing more and more distant. If you are the required glue to hold them together, as she continues to distance from you, she will also distance from D. If you leave the two of them to work it out now, there is a better chance it will preserve their relationship independent of what happens between you and stbx.
I was always the glue between my H and my kids. Now they cannot relate to each other at all. He is very, very slowly making more effort. In fact S volunteered last night that H is sending lots of weepy texts about how much he misses S. This is a big improvement to Mr. Confident not having any time for his kid.
The more I have backed away, the more he has stepped up. The gulf is so huge though that it is going to take some time before he mends it enough for anyone to see the progress.
