katelyn, congratulations on recognizing that you need help. That is the first step to getting better.

So maybe the reason to tell them if you need their help to get a psychiatrist so you can get medicines to stabilize your emotions or a therapist to help root out the causes.

Okay so maybe you need to check out what their insurance would cover. Maybe rather than talking about the specific problem, you could ask them if their insurance would cover visits to a therapist (most cover 26 visits a year, but some less) or to a psychiatrist to SEE if they think you need medicine. By talking first about the solution they may be less panicked. Even if you only tell them you are depressed that might be enough to convince them to let you see a professional. If not you could say your emotions are interfering with school.

I am trying to find the point that they see a critical need. You can eventually tell them if you don't tell them now, but if that is what it takes to get you professional help then certainly tell them. Tell them as much as they can hear and still get the professional help you need.

I am not suggesting withholding info just telling them as much as they can hear

How does that sound?