Martha does not ask Clark how he knows that Lionel knows his secret. The answer would have been alarming. Jonathan, who is dead, told him. Martha immediately concludes that Lionel was behind the blackmail that he claimed to have sorted out.
What an episode! Lionel surely proves himself. He is willing to die for Martha and Clark and he keeps Clark's secret from Lex. But surely Lex now has sufficient evidence that Clark has super-speed and super-strength? Clark is far too hostile towards Lionel.
Working at the Planet has made Chloe even more glamorous.