I wouldn’t say autism is “worse” than schizophrenia, to be honest. It’s a spectrum and everyone on it has different issues but also different strengths. Many autistic people lead happy, fulfilling lives but it might take them a while to develop that.
As for what your dad says, it’s not really true. Some mental illnesses can be alleviated and/or managed better with therapy but I don’t believe there are many, if any, illnesses that can be eradicated through therapy.
I hope you can find someone who can help you. We can’t make diagnoses here, although we can offer advice and support where it’s appropriate.