I would never give advice like this to an individual.
Some people who think they need professional help (such as counseling) and don't get it because their parents interfere or think they don't need it, go outside of the home and seek it anyway.
They might go to the school they would attend and approach the school counselor and explain that they are in this situation. The school counselor would be obligated to report such a problem to whatever social services are available in the area. Others would go straight to social services and skip the school counselor. If they didn't know how to find social services, they might start at a police station or a church.
The reason I would not directly give advice to do such a thing is because it puts things in motion for people to investigate their parents and the homeschool situation and all.
While I would not give YOU such advice, were it me- I would seek help outside the home. I have a history of a need for professional counseling and I wouldn't want to wait until it was too late. I hope you understand what I am saying.