Hate to say this but breaking up will be the best for you. If you think that after marriage, things will get better ... chances are it'll get worse. Living with such person is a mental torture. Unconsciously you'll start to accommodate her more just to have peace and because you don't want her to 'meletop'. However, the more you do that the worst her behaviour will become. Unless she's willing to change (almost impossible), walk away bro ...