When a person embraces Islam,there are two possibilities : the parents may be happy or else not be. For that the revert needs not to bare pain. Must understand that Hidayat ( guidance ) is given by Allah.whom Allah loves and likes gives the gift of Islam.So needs to be honorable for that.
Secondly, There are many instructions and guidance in Islam to oppose the deeds against any of the part of Islam.With parents whether they aren't muslim needs to be polite and gentle,cause they are parents, although (unbeliever). But not to forget,never to obey them when it is the case against Islam. Islam has given full right to oppose them,when its matter against shariat . There are many aayats in Qur'an and hadiths ,regarding that. unable to quote as the topic would be very lengthy else.
One must say them that if they talk against hijab, I feel much pain.and as You wear your clothes according to your religion, Islam teaches me to wear Hijab,what's wrong ? and as I don't interfere your personal matters, I too don't like such interference. such incidents had been with the companions (sahaba radhiallah), but they had smelt the sweetness of islam,so none could change their path from islam.
So, finally needs to be courageous ,gentle,humble in matters but when it is the case of Islam,never to give up.cause we muslim know,what is truth and what is false. each one would cut,what he/she has sown. A muslim is an allrounder,cause Islam has taught how to live 24 hour life.
And pray for them that they too embrace islam. duas,lot concerned
try it, don't forget to ask matter to some mufti/qari/pious person.InshaAllah, things would be ok. What Allah laid in my mind i wrote.
Allah knows best.
Lillahil hamd.