Comment by h0l0cube

The only ethical 'business model' I could see here is a donation-based non-for-profit that keeps the lights on. It might be worthwhile partnering with a non-for-profit that's already in the mental health space. They can funnel grant money into this, and probably have enough advertising budget and brand to get much broader reach. Otherwise it's fine to keep it small as your passion project and not exploit your users for growth.