If you want to major in psych, major in psych. Trust me, you would be surprised how many psych majors (and MH professionals!) struggle with mental illness! I'm bipolar, and I'm a proud psych major who wants to be a psychiatrist.

Also, there is much more to psychology than clinical psych. If you find that learning about MH disorders is too triggering for you, you can take classes on other fascinating psych topics, like cognitive, social, or developmental psychology.