زَعَمَ الْعَوَاذِلُ أَنَّنِي فِي غَمْرَةٍ، صَدَقُوا وَلَكِنْ غَمْرَتِي لَا تَنْجَلِي
The reproachers claimed I was engulfed in a troubled state; they spoke truly, but my state does not clear.
The first statement prompts the implied question, “Were they right in their claim?” Sadaqu answers exactly that question and therefore stands without a wāw connecting it to the preceding clause.
The later wa-lakin introduces a contrast. It should not be confused with the omitted coordinating wāw between the initial claim and the answer to the implied question.