I am using 

     catch (Exception e){ 
       ApexPages.Message myMsg = new ApexPages.Message(ApexPages.Severity.FATAL,'my error msg'); 
       ApexPages.addMessage(myMsg); 
    } 

And have `<apex:pageMessages/>` in my VF page. 

still i get my custom message  + the salesforce standard exception displayed at my page. I want only my message to be shown.