Everyone here has been where you’ve been. We’ve all committed sins that we are deeply ashamed of.
When I teach adults in RCIA, the greatest fear they have is confession. I tell them, “In the confessional, talk about what bothers you.”
I have yet to lose anyone – and virtually all of them come out smiling, with a great weight lifted from their shoulders.
I recommend you read “Angela’s Ashes.” Frank McCort, while a young man had an affair with a girl who had tuberculosis and she died. He was in agony, since she died with a mortal sin (their affair) on her soul. He couldn’t go to confession.
He did go into church and sat in front of a statue of Saint Francis (his namesake.) One day, a priest, seeing that he seemed to be troubled, stopped and talked to him. Eventually the whole thing came out. The priest reassured him – the girl died in a Catholic hospital and the nuns would never let her die with a sin on her soul.
Read the book, and rent the movie (you can’t understand the movie unless you’ve read the book first.) See if you aren’t moved when the priest stands to go, and quietly says, “Ego te absolvo.” (“I absolve you.”)