Praise be to God for your new faith!!
I’m Catholic, so I have a rather, let’s say, pointed opinion on the matter.
But I’ll sum it up in this wise. Rewind back to the time o the Reformation. If the Church you were “reforming” called you a heretic and excommunicated you and said you were damned to hell, a prideful and stubborn man might well strike back the only way he could—by attacking the very principle of its authority.
You can wear excommunication from an Apostate Church like a badge of honor. The True Church not so much.
So it’s completely understandable psychologically. Calling Catholicism Apostate is an attempt to mitigate the Reformers’ sin of heresy and schism by saying it was absolutely justified and necessary.
Only problem is that historical evidence for said apostasy is absolutely, categorically non-existent. It never happened.
It is a greater sin to stay in an apostate denomination and not attempt to bring them back to Truth. Catholic apostasy? Let me count the ways. Indulgences or the idea you can buy your way onto haven. Elevation of Mary to co-redemptix with Christ, Queen of heaven and other blasphemous and unbiblical titles. Salvation by works only to members of their particular club. Elevating their leader (pope) to Christs representative on earth calling him holy father and other blasphemous titles. Robbing believers of the security of salvation. Doctrines like purgatory and denying the sufficiency of Christs atonement ( you still have to pay or suffer for your sins in purgatory. Thats a short list for starters
"One indeed is the universal Church of the faithful, outside which no one at all is saved, in which the priest himself is the sacrifice, Jesus Christ, whose body and blood are truly contained in the sacrament of the altar under the species of bread and wine; the bread (changed) into His body by the divine power of transubstantiation, and the wine into the blood, so that to accomplish the mystery of unity we ourselves receive from His (nature) what He Himself received from ours."
--Pope Innocent III and Lateran Council IV (A.D. 1215)