I'm sorry you are going through this now. I had a very similar situation with my dad when I told him first about my eating disorder, then when he found out about my si.
Is it possible for you to approach the teacher again, as suggested, or maybe go to a guidance counselor and talk to them about your depression and the reaction from your parents? The suggestion to go to your doctor is also a good one...

It's very hard to try to seek help, especially when you have had such horrible experiences when asking for help. I hope you can find some support...