U, sorry that it's turned out this way with the kids. From the beginning, telling the kids was the number one issue for me. I avoided it for seven months while we still lived together, only telling them two weeks before S. But we did it together and planned out what to say ahead of time. If it hadn't happened that way I would have been devastated.
As far as child sharing, a court is not going to overrule something you both agree on. My state ages out at 18, so if yours does, you only need to consider the 15 year old as far as a time sharing schedule. S18 can stay where he wants. But even D15 is old enough that she can participate in the decision. My D was 16 when H moved out, and we didn't set a schedule for her. She stays with me full time, has dinner with her dad when they both feel like it. Sad to me, but I'm not going to force more on her, and wisely, neither is STBX.
It's all hard stuff, U, and not what you wanted. But you'll continue to be their rock and that's exactly what they need right now.
