Marriage can be postponed for 2/3 years. Even if you marry now with this frame of mind, it's not going to help you in the relation.
First of all you need some peace of mind and calmness inside you to deal with the situations. Start practicing pranayam along with some stretching and other exercises. Maintain a sleep pattern and eat good food. By good i mean, less of fried and packaged stuff.
Join your family business but keep the working hours similar to your articleship period and study in morning/evening and weekends/holidays. Do discuss this system with your parents or elders so that there is no confusion later on.
This way your frustration or suffocation will be less which may happen if you just sit at home and study and study.
Initially it may look difficult but keep doing it on a daily basis to get into a flow and rhythm.
Don't rush to give the exams at the earliest. First decide how much time you need to prepare thoroughly for the exams. According to it, select the exam term. Best wishes.