Oh, this part made my heartbreak for Clark. I felt a little miffed that he seemed to be a bit self-absorbed and not realizing that his words might hurt Martha and Jonathan, but then I decided that we only saw his initial reaction and later he probably realized it.
It was a truly horrible way for him to find out the truth - or part of it. At least if he had heard it from Lara, she could have explained the reasons and he would have seen her guilt on her face which may have lessened the pain.
And Lara's dream was heartbreaking as well. The guilt she carries around over what happened to her son is so awful. I hope Clark and Lara meeting helps to ease both of their pain.
