It is better that you keep at it and try and work through the issue. The key to working through any trigger though is to identify why it triggers you in the first place, as its not the song or issue at hand that is actually the problem, its the underlying emotion likely stemmed to some trauma or traumatic thought stored in your brain. Identify and attack the cause, as the trigger is just that.... a trigger to something deeper, of which really has little to do with the problem at hand and is just a sign something deeper is wrong.

You do not avoid triggers, you face them head on and work through them to find the cause. You deal with the cause and then you continue exposure to the trigger until such time as it is no longer a trigger for you. Very rarely will a trigger be so significant that I would say to avoid it. Only in rare circumstances is that applicable, usually with suppressed memories where you simply cannot identify the cause until your mind is ready. Even then, you store it, avoid for the time being, then deal with the cause when your brain is ready to. You must face all fears if you want to restore any semblance of normality to your life with PTSD.