I have selective mutism and people keep criticizing me!?

Everyone keeps telling me I'm not normal, especially my parents. I overhear them talking all the time, but when they're around me they lie and sugarcoat everything. Kids at school think I'm weird and so does every single person I've ever met. I'm feeling down and I need to find someone that understands me. How can I conquer my fear of speaking and social phobia? Please help!