He is Catholic. Maybe not practicing or acting very well. But he is Catholic. He may not be a good pope, but he is pope. Sedevecantism is a result of personal pride. Christ promised that the gates of hell would not prevail. Things may look bad, but Christ will protect the Catholic Church and preserve it til the end of time.
I'll pray for your reversion.
Something being officially taught does not mean it hadn't been taught before. The Church uses its official teaching authority to clarify doctrine that is held but is coming into dispute because of the times. If a doctrine does not come into dispute, then there is no reason to clarify it.
Also, 2 Thessalonians 2:15 says, "Therefore, brethren, stand fast and hold the traditions which you were taught, whether by word or our epistle."
Not every truth is taught explicitly in the Bible. Even if it was, there is still the need for an interpreter. Otherwise, you get everyone starting their own congregation because they think they know how to interpret it correctly and everyone else was wrong for 2000 years. This is why Christ instituted the papacy and sent the Holy Spirit to preserve the Church.
That is a common falsehood people spread to discredit the Church. The truth is that the Roman Empire try to prop up the Arians, an early heresy, to supplant the Church. They failed as have all that tried to destroy God's Church.
If you are sincerely interested in this question Trent Horn has good videos on YouTube about it. GK Chesterton has also written many good books about Catholicism.
I'm not defending him nor do I particularly like him. However, that doesn't make him not the pope. He could come out as gay and livestream orgies, but he would still be the pope. Popes are not guaranteed to be holy, just infallible.