I knew there would be problems involving Mattie, but I didn't expect this. They were so close to completing the merger, and now the hidden mine has exploded and created havoc. I can't imagine how badly Lois might be injured. I can barely imagine the horror that Mattie is about to face - she lost control and physically hurt her mother. Clark will blame himself for not being fast enough to save Lois, not being a good father, not teaching Mattie better, and it's worse now that it was when the story started.
This incident has the potential to destroy this family. It's going to take everyone - Clark, Lois, Mattie, Martha, and JP - working together to get past this possible disaster. I think there will be a peaceful resolution, and I think Lois will decide that yeah, she and Clark should legally tie the knot. But the relationship between mother and daughter has been seriously strained. Mattie wouldn't have cracked like that if she'd been confident of her parents and their intentions. Because Lois wanted to do things her own way, without considering the feelings of others, she's largely responsible for this. Lois cannot continue to ignore her children's psyches. Children are indeed resilient, but they depend very strongly on their parents to be their lifeline, their port in the storms of life, even as adults.
Even though Mattie really didn't give off a lot of warnings, she gave off enough vibes that, while this is a surprise, it's not out of character for either her or the story line. I knew something bad would happen, but I sure didn't see this coming. Excellent storytelling, Annie. Keep it up!