Public revelation stopped with the death of the last apostle this comes from the Vatican II council and more specifically the document Dei Verbum or the Dogmatic Constitution on Divine Revelation.
Dei Verbum, 4
Then, after speaking in many and varied ways through the prophets, “now at last in these days God has spoken to us in His Son” (Heb. 1:1-2). For He sent His Son, the eternal Word, who enlightens all men, so that He might dwell among men and tell them of the innermost being of God (see John 1:1-18). Jesus Christ, therefore, the Word made flesh, was sent as “a man to men.” (3) He “speaks the words of God” (John 3;34), and completes the work of salvation which His Father gave Him to do (see John 5:36; Divine Revelation 17:4). To see Jesus is to see His Father (John 14:9). For this reason Jesus perfected revelation by fulfilling it through his whole work of making Himself present and manifesting Himself: through His words and deeds, His signs and wonders, but especially through His death and glorious resurrection from the dead and final sending of the Spirit of truth. Moreover He confirmed with divine testimony what revelation proclaimed, that God is with us to free us from the darkness of sin and death, and to raise us up to life eternal.
The Christian dispensation, therefore, as the new and definitive covenant, will never pass away and we now await no further new public revelation before the glorious manifestation of our Lord Jesus Christ (see 1 Tim. 6:14 and Tit. 2:13).
To quote the Catechism:
“Throughout the ages, there have been so-called ‘private’ revelations, some of which have been recognized by the authority of the Church. They do not belong, however, to the deposit of faith. It is not their role to improve or complete Christ’s definitive Revelation, but to help live more fully by it in a certain period of history. Guided by the Magisterium of the Church, the [collective sense of the faithful] knows how to discern and welcome in these revelations whatever constitutes an authentic call of Christ or his saints to the Church. Christian faith cannot accept ‘revelations’ that claim to surpass or correct the Revelation of which Christ is the fulfillment, as is the case in certain non-Christian religions and also in certain recent sects which base themselves on such ‘revelations’” (Catechism of the Catholic Church 67).