Isabella's misfortune all stemmed from Blanch. Anyway, since she could no longer be with Felix, it didn't matter to say such things.
Felix only felt pity for Isabella; no one expected things to turn out this way.
"If you still care about our feelings, then publicly announce that you and Blanch have nothing to do with each other. You will handle this matter fairly and justly. As long as you're not involved with Allen, Blanch won't have a single supporter. Let's see how she manages."
Previously, when Blanch was in a desperate situation, both Allen and Felix wanted to help her. Now that both had withdrawn, would anyone still help Blanch?
Felix felt helpless and could only do this. Compared to Blanch, Isabella's pain would last a lifetime. If he didn't help her resolve it, Isabella might be ruined for life.