No…there is no being forced to decide between fidelity to Tradition or fidelity to the Successors of the Apostles. Such an assertion shows the extent to which you are in error…as does your previous comment, which you deleted but which I saw and which I hope the moderators also see,
The concept upon which what Pope Pius IX writes actually rests has been superseded. Just as the issue of how to deal with the theological concerns the held back the dogmatic definition of the Immaculate Conception were superseded by the theological concept of prevenient grace.
You should be thanking God to live in the aftermath of one of the greatest events in the history of the Church – The Second Vatican Council.
Not since the 11th century have we had such a succession of men of outstanding holiness and gifts, raised to the altars, who occupied the Chair of St. Peter, one after the other.
Pope Saint John Paul II well articulated where the duty of the faithful lies in face of the unspeakably evil act of Marcel Lefebvre and his disciples.
The root of this schismatic act can be discerned in an incomplete and contradictory notion of Tradition. Incomplete, because it does not take sufficiently into account the living character of Tradition, which, as the Second Vatican Council clearly taught, "comes from the apostles and progresses in the Church with the help of the Holy Spirit. There is a growth in insight into the realities and words that are being passed on. /…/ But especially contradictory is a notion of Tradition which opposes the universal Magisterium of the Church possessed by the Bishop of Rome and the Body of Bishops. It is impossible to remain faithful to the Tradition while breaking the ecclesial bond with him to whom, in the person of the Apostle Peter, Christ himself entrusted the ministry of unity in his Church
We are always to choose the living Magisterium.