If I reach you, heartbroken, it will not be little; even this neem-poisoned heart has faced an apocalypse.

Mir Taqi Mir compares the pain of heartbreak to a severe physical illness. The poet says that even if his wounded heart reaches the beloved, it is nothing compared to the internal agony. The 'neem-kushta' (a persistent fever or sickness) has caused such a catastrophe in his chest that the emotional pain is overshadowed by the sheer physical torment. It's a beautiful blend of romantic suffering and physical decay.