If sister Lucia of Fatima accepted Vatican II and the Vatican II Popes, then I must do so as well. After all, the blessed virgin Mary told sister Lucia that she would go to Heaven. So sister Lucia is a Saint.
Indeed, she is a Saint. Our Lady promised that Sr. Lucy would attain to the celestial heights after much horrible suffering, the details of which we may never know in this life. However, that promise did not necessarily entail a sort of "infallibility" regarding theological disputes of a polemical nature.
Sr. Lucy was a Carmelite virgin of eminent sanctity, a worthy daughter of St. Teresa of Jesus and St. John of the Cross, having attained unto the apices of the mystical ways of prayer and contemplation, and mysteriously paralleling (though in a hidden way, much akin to the interior life as taught and lived by the Little Flower) the life and prodigies of her spiritual Father, St. Elias the Prophet, the great Founder of the Carmelite Order.
Sr. Lucy was not part of the world, being detached from self and all other created things, and therefore not knowing of the troubles and anxieties of the world, yet offering reparation and sacrifice for them. Like the great Padre Pio, if she obeyed Rome after "Vatican II," she did so in good faith, cherishing the dogmas of the infallibility and primacy of the Roman Pontiff as defined at the Vatican Council, as do Catholics entrapped in the "Novus Ordo" who are of good faith and of irreproachable morals, and are (this is most important!)
devoted to Our Lady and her Most Holy Rosary.
It is my personal opinion that the Third Secret, other than explaining the crisis in the Church as only Our Lady could (how that would be, we may never know in this life), also explains what Sr. Lucia said in a later interview about how the Holy Rosary was given a new and more potent efficacy for our times: as some have said many times hitherto, the Holy Rosary is the key to ending these calamitous disasters that have befallen Holy Mother Church.
So my advice for you and everyone here is to persevere in the devout recitation of the Holy Rosary and observe the message of Our Lady at Fatima, which is nothing more than an echo of those immortal words that Mary Most Holy spoke (the only public pronouncement of hers recorded by the Evangelists): "Whatsoever He (that is, Our Lord Jesus) shall say to you, do ye" (St. John ch. ii., 5).