Let's just flat out state the implication of Lana's outbursts to Lois - at the start of the episode Lana laments the fact that Clark 'clearly didn't love her enough' when they were kids to come back and tell her everything and Clark doesn't disagree with this, he just says sorry. That was the thing she was pissed about more than anything. We then see Lana thinking in the diner before she goes to the Kent farm to attack Lois for DARING to not tell her all her family secrets despite only really knowing each other for less than a year.
Let's be real - Lana is pissed that Clark, who she now knows is Superman, loves Lois far more than he ever did her, trusted her with his secret and married her. THAT'S what she's angry about and it shows that Lana, a woman in her 40s with 2 children, is jealous of what Lois has because SUPERMAN wants Lois and not her.
It's pretty pathetic and is likely urged on by her own husband's infidelity. But I hate that they've decided to write this female friendship like this when I liked it before.