How many sins are too many? Well, one single sin is "too many". Sin is an abomination before God because sin put Christ to die on the cross.
The first biggest sin is "not to love God", the second one is "not to love our neighbour". When we sin we try to justify ourselves, but who can justify himself before God? If we don't confess our sin, then we will forget it and we will authorize ourselves to commit more sins, the more sins we have the more we forget that Christ had to suffer for our sins and pay with his life for them. The more sins we commit and keep unconfessed, the denser will become that cloud that separates our souls from the light of Christ who is the light of the soul. When the heart becomes hardened by sin, it is very difficult for the soul to feel repentance because our sins give away our souls to satan. When we sin we despise Christ and his suffering, we reject the commandments of God and we obtain a sure ticket to hell.
What can we do?
Jesus instituted the Priesthood so that we could have our sins forgiven. When we are in a state of sin we are unworthy to come before the Presence of God, therefore he has made it simple for us, but we must humble ourselves before a man that has been authorized to forgive sins in the name of Jesus Christ the Lamb of God who takes away the sins of the world.
The Lord says:
Jesus said to the apostles and to those who consecrate themselves as priests
If you forgive people's sins, they are forgiven. If you retain people's sins, they are retained.
Therefore, repent and turn to him (Jesus) to have your sins blotted out,
It is by the Divine Mercy of my Heavenly Father that I came to the world to die in order to forgive sins.
My sufferings and death tell sinners how much I loved them that I was prepared to die to give them eternal life. Sin destroyed the life of the soul since the beginning of the world, I have come to give eternal life by my forgiveness.
The soul of the sinner that doesn't repent is darkened by sin which extinguishes my light in him. The punishment for the sinner that wilfully remains and dies in sin is eternal death, which is an eternal state of punishment in the fires of hell.
I offer my Divine Mercy to everyone, stop offending God, come to my Mercy while you still live; after death, you won't find Mercy but Justice.