Q. 1. If I go to confession to one of the priests from the Society of Saint Pius X, will the Sacrament be valid?
A. 1. On December 8, 2015, the Solemnity of the Immaculate Conception, Pope Francis stated that the priests of the Society of St Pius X, which presently lacks official canonical status in the Church, would have full faculties from him during the Jubilee Year to hear the confessions of “those faithful who for various reasons choose to attend [SSPX] churches.”
Furthermore, Catholic priests throughout the world will have the faculty to forgive the sin of abortion during the year of Mercy.
In many places in the world, absolution for the sin of abortion had been reserved only for the bishop of the Diocese. The sin of abortion carries with it a "latae sententiae," or automatic, excommunication, meaning it is so grave a sin it separates a person from the Catholic Church and forbids participation in the sacraments. Only the bishop of a diocese has the ability to extend the Church's forgiveness to a person who incurs an excommunication. He may, however, on certain conditions and occasions grant that power to priests subject to him.
On Sunday November 20, 2016, the Solemnity of Christ the King, the Holy Father's newest letter declared, "The provision I had made in this regard, limited to the duration of the Extraordinary Holy Year, is hereby extended."
In response to your question, you can now go to Confession to a priest from the SSPX with assurance that the Sacrament that you will receive is valid.