Lex wanted the pain. He felt he deserved it with Helen laid up in the clinic, all broken and bruised because she'd come back to save him. Granted, he was grateful since without her he'd have been dead, but he hated how hurt she'd become in the process. It was probably childish, but the pain from Freddie's fists felt like some sort of minor redemption.

Though hitting Freddie back was purely in Anatoly's defense.