What was the significance of the temple curtain being torn?
Not that you will listen, but I will give you the answer.
What was that part of the Temple used for? It was the Holiest of All where once a year, Yom Kippur (Lev. 16) was performed and the covenant between God and man was renewed by the forgiveness of the national sins of the people.
When Christ died, that ended the covenant. We know that it ended the covenant because God in His Word has likened the covenant to a marriage. In fact, the ancient heretics, the Puritans, used to refer to "the covenant of marriage" in their ceremonials (even a blind pig finds an acorn of truth once in a while). In Hosea, God likens His relationship to national Israel as a marriage, with His spouse playing the harlot with idols and false "gods."
Therefore, thinking this analogy through, we come to realize that when a spouse dies, that covenant of marriage is ended. This is true whether the spouse dies of natural causes or is killed by the other spouse. Either way, there is no longer a relationship and no longer an "other" in the covenant, which means that there is no covenant.
Jesus, God in the Flesh, is murdered by His spouse, national Israel, and the covenant is over. The sign that this is over is that the veil is torn from top to bottom. This exposed the Holiest of All to the whole world. A place where only the eyes of a high priest could see into was shown to the whole world. This desecrated the Holiest of All and thus made it unfit for any further use.
The tearing of the Temple veil is the sign that the covenant is over, and it took place at the same time that Jesus said "It is finished," which means that both the work of salvation is finished, and the Old Covenant promising salvation was also finished.
That's your answer. All your questions about the Catholic faith can be answered by coming to understand the Covenant of God, how it works, and what are its principles. And if and when you come to properly understand the Covenant of God, it will return you to the Catholic faith because every Protestant denomination out the violates one or more of those five working principles.