What can I say at customs at the airport going back into Canada to save myself?

From another secondary security screening (when they take you in a private setting and inspect every item in your bags and interrogate you). This happens every time I go back to Canada from Peru. I tell them the truth that I was on vacation or visiting my wife and baby and they say ok and then put red on my declaration card and say nothing and then I have to go to other place when they inspect and interrogate me. They treat me bad and unfairly and they are rude and scary. I hate it and it�s given me major sustained psychological damage. Do they discriminate against people with disabilities? Because I have a social disorder (form of autism) which makes me look weird and suspicious and lying, but it isn�t by intention. I get so nervous going back, and for good reason! It�s not fun for me. I want an immunity from this. Can someone please help me?