how would one say: bless me for i have sinned in latin?

Answer 1

In the Biblical Latin style it would be

Benedic me enim peccavi (bless, singular)
Benedicite me quia peccavi (bless, plural)

"for" seems to be "enim" or "quia" mostly in the Vulgate.

Answer 2

My first impulse is to say "benedicta me, quod peccavi."

The Book of Common Prayer apparently says
"Iube benedicere, quod peccavi."
Literally, "ask that I be blessed, because I have sinned."

Most confessions haven't been made in Latin for decades, if not centuries, so it's hard to find the exact ritual phrase.

Answer 3

Here is an Act of Contrition in English and Latin:

O My God, I am heartily sorry for having offended Thee and I detest all my sins because of Thy just punishments, but most of all because they offend Thee, my God, who art all good and deserving of all my love. I firmly resolve, with the help of Thy grace, to sin no more and avoid the near occasions of sin. Amen.

Deus meus, ex toto corde poenitet me omnium meorum peccatorum, eaque detestor, quia peccando, non solum poenas a Te iuste statutas promeritus sum, sed praesertim quia offendi Te, summum bonum, ac dignum qui super omnia diligaris. Ideo firmiter propono, adiuvante gratia Tua, de cetero me non peccaturum peccandique occasiones proximas fugiturum. Amen.

With love in Christ.