I understand your dilemma. The I.B. program offers a lot of benefits, but you are really struggling in this program this year.

Perhaps, before choosing to leave the program, you can try to look into whether or not you have the option to sign up with a different teacher next year. You are saying that you are going to complete this year with your current teacher anyway. If you are able to get into a second language class next year with a better teacher, then that sounds like it could help reduce your stress. If the teacher is the primary problem, and if this problem could be solved next year, then perhaps you can stay.

If that does not sound like a viable option, then of course you can leave the program next year. It is important that you reduce overwhelm and take care of your mental health, because that is also an investment in your future. It also sounds as though you will be able to put more effort into the rest of your classes if you aren't in the I.B. program. This could mean that you'll be getting above-average grades, instead of average. I'm not sure how it is in your country, but employers might be looking at your grade point average (GPA), and not only looking at whether or not you are in the I.B. program. Employers also look for experience and other skills. As you gain more experience in your field, you will be able to get higher-paying jobs.