When I was a Catholic, MANY years ago, I was absolutely, totally, completely, 💯% convinced I was going to Hell. I KNEW it. Obviously, I don't think that way now.
I just thought of something. Do you suppose, it is also the sin of presumption in reverse, to presume one will go to Hell? A conundrum?
Rome says
No one can be absolutely certain of his or her salvation unless--as to Magdalen, to the man with the palsy, or to the penitent thief--a special revelation be given [that one is part of the elect]. (Trent, Sess. VI, can. xvi).
No one, moreover, so long as he is in this mortal life, ought so far to presume as regards the secret mystery of divine predestination, as to determine for certain that he is assuredly in the number of the predestinate; as if it were true, that he that is justified, either cannot sin any more, or, if he do sin, that he ought to promise himself an assured repentance; for except by special revelation, it cannot be known whom God hath chosen unto Himself. [Trent, The Sixth Session, CHAPTER XII, http://history.hanover.edu/early/trent/ct06.html]
It is one think to deny that one can know that one now has eternal life, (1Jn. 5:13) and will go to Heaven as a believer, which is not presumption by God's promise, and it would be sin to believe Christ will abandon believers, and that believers will not go to be with the Lord after this life, which leaves the only sin of presumption in this regard to be that of presuming you could never choose to walk away from Christ in unbelief - including not believing "that he which hath begun a good work in you will perform it until the day of Jesus Christ," (Philippians 1:6) - and die as a unbeliever, one fallen from grace, against which Scripture warns believers. (Heb. 3:12; 10:39,39; Gal. 5:1-5)
Likewise it would not be a sin of presumption to believe you would go to Hell as an unbeliever, but it may be be a sin of presumption to believe you will never come to saving faith in the risen Lord Jesus, unless you know you have committed the unpardonable sin.
And indeed you were before your Biblical "day of salvation," but with the old emphasis on guilt and perpetual penance even for past sins done before conversion (while modern Rome basically sends Teddy K Catholics off to glory), it is no wonder you were convinced I was going to Hell:
From a Traditional RC site:
Properly viewed, having a perpetual reminder of one’s misdeeds in the form of public “shunning,” is not cruel, but rather in itself a great mercy to the woman who might thereby bewail her sins for the rest of her life.
This is what the first Pope of the Church did all his life, after the Passion. It is a solid tradition that there were caverns under the eyes of St. Peter caused by the tears that he shed every day for his public thrice denial of Christ. St. Mary Magdalene spent the last decades of her life as a hermit in a cave doing penance for her past sins. — http://www.traditioninaction.org/religious/k011rpUnwedMothers_Stretenovic.html