And when you stand praying, if you hold anything against anyone, forgive them, so that your Father in heaven may forgive you your sins. ” ~Jesus
Jesus proves through His Words you can have forgiveness of sins through prayer.
He says when you stand praying forgive others and God will forgive you.
Well, you can confess your sins to God. He already knows what you're doing but acknowledging your sins in prayer before God is a step in the right direction.
It's between you and God. He will forgive your sins through prayer directly.
You don't need your priest to accomplish this. You don't need to be dunked in water to accomplish this. You don't need a sprinkling of "holy" water to accomplish this. You can come before the Lord in prayer and communicate with Him directly.
You can be yourself before the Lord and pray/communicate with him directly.
How do you know if you're holding something against someone?
When you go back to that point in time over and over again and rehash it by holding on. When you can't seem to let something or someone go.
Ask God directly through prayer to help you with that grudge and to show you a better way.
Again, you can do this directly through prayer.