I suspect this is a matter of perspective. Your parents are dealing every day with desperate situations. From their point of view, you have opportunities that other people can only dream about. They may be missing that, for you, your situation is indeed as painful and as worthy of respect as the situations of the people they are trying to help.
You’ve tried explaining and complaining. It hasn’t worked. Your other option is to find alternatives for yourself and present them to your parents as practical suggestions. No, in an ideal world, you wouldn’t have to do this. But you’ve already tried turning to them for help and it hasn’t worked. So let’s try a few other things:
First, consider that learning French is an opportunity, not an obstacle. If you are worried about college admissions in the future, be assured that admissions officers do take into consideration unique situations like your own. Clearly, your past record demonstrates that you are a good student. The fact that you are even able to achieve at a 50% level in a language you are just beginning to understand is remarkable. You could decide to relax your focus on grades and to keep at it with the idea that your challenge this year is to become as fluent in this new language as you can. Someone as intelligent as you are will figure out a way to catch up on whatever you miss academically.
Do talk to the school counselor if there is one or a trusted teacher about your situation. See if there is a way you can get some tutoring in both French and the subjects you feel you are missing. See if there is any possibility for help transferring to an English language school. There might be scholarships available that your parents don’t know about.
You didn’t mention why living for a time with your father would be a bad idea. It might be a reasonable solution.
Consider transferring to a boarding school in America. Many of the private schools in the U.S. are attended by a large number of international students. Many are as challenged by English as you are by French so the schools have provisions for English as a second language (ESL) student. You would be an asset to a class because you would be able to empathize with how difficult it is to perform in a new language. Again, there may be scholarships.
I wish you well.