Leah knew that Stacey's world was crumbling down on her, so she said, "I know your world is falling apart, but it can't ever crumble completely. You have us" She indicated to herself and Sky. "to hold it together for you."
She had never had a divorce in the family, but both of her parents had died long ago... did that count? Of course, death was much different, harder in some ways, yet easier in others.
"I can't try to pretend to know what you're going through, because I don't. I also can't tell you that it'll be easy, because it won't. But I can tell you that if you ever need anything, anything at all, no matter what it is, you can ask me." Leah told Stacey the absolute truth, and all of it too. She didn't want to make this harder than it already was.