Forgive and You will Be Forgiven

Psalm 55:

Steps to take when someone you love has hurt you badly (based on Psalm 55):

(For some Bible translations, one must be added to the verses of Psalm 55).

1. "Cast your burden on the Lord, and he will sustain you;" (Psalm 55:22a,
   1 Pet 5:6–7). We should come to Jesus with our burdens (Mat 11:28–30). 
   A burden is usually about things that we aren't sure how to respond and what to do about, and makes us frustrated. It can be an injury, a disappointment,
   or even decisions that we have to make. Many times it involves fear due to some kind of pain. Then we must remember that we are getting closer 
   God the Father in the righteousness of Jesus (not in our own strength),
   in the name of Jesus (Heb 4:16). My sin has been atoned for through Jesus, see The Atonement. See also  Psalm 51: Coming to God when we fail. I have to ask God repeatedly in prayer to help me deal with the problem properly.
2. Complain to God and not to men (Psalm 55:1–2, 17). God won't be offended, people might. Don't speak evil of anyone (Titus 3:2).
3. Tell the Lord exactly how you feel. King David did (Psalm 55:4–5).
   It's called relationship with the Lord and not religion.
4. Give voice to faith in God, see Faith in Faith, Hope, and Agape Love. During prayer express statements of faith in God. David did so (Psalm 55:16, 19, 22).
5. Forgive as you have been forgiven, see below.

Forgive as you have been forgiven:

Forgiveness is a central teaching in the Christian faith. Jesus gave his life for us, which means that if we confess Jesus as our Lord, and ask him to come into our lives, he forgives us our sin, but expects us to forgive those who have wronged us
(Mat 6:12). If we don't forgive people their trespasses, God won't forgive ours,
and in fact we risk being lost forever (Mat 6:14–15, Mark 11:25–26), see time
54:31–1:00:27 in Matthew 6:1-15 – Life in His Kingdom: How to Give and Pray.
See also the comment on the 6th commandment in the The Ten Commandments.

Apostle Peter asked Jesus how many times he would forgive, if it was seven times. Jesus answered him that it isn't up to seven times, but seventy times seven 
(Mat 18:21–22, Luk 17:3–4). What Jesus means is to forgive unlimited times.

The moment another person wrongs me, I must forgive that person. Only by forgiving that person will my soul be free. If I don't forgive that person, I sin and jeopardize my own forgiveness from God. Whether or not the person repents and asks for my forgiveness makes no difference. I need to forgive that person, who
has to deal with God about his wrongs, but that is between that person and God. Whether or not this person reconciles with God is irrelevant to this one truth:
I must forgive this person. See The Parable of the Unforgiving Servant. See
it explained at time 3:04–7:33 in This BIG Lie of Satan Sends Believers to Hell. 
To walk in forgiveness is to walk in freedom. To walk in unforgiveness is to walk
in slavery and makes us bitter.

If someone has wronged me, who doesn't see that he has wronged me, I must forgive this person before the Lord. I don't need to tell a person he's forgiven, especially if he thinks he has done nothing wrong to me. To forgive a person before the Lord means to release that person from a debt. It's then important not to treat this person differently than anyone else, and not hold that guilt over his head.

If I have wronged someone else, it's good to admit and confess that I have wronged that person. If so, it's enough to do it directly to Jesus Christ, but I can also do it to the person I have hurt, see also time 45:55–46:55 in September 2024 Bible Q&A.

God demands that we show mercy to our fellow human beings and that we forgive each other (Col 3:13, Eph 4:32, Mat 5:7).

Jesus even said we should love our enemies and pray for those who persecute us
(Mat 5:44–45, Luk 6:27–28, Rom 12:14, 17–18). A good way to prevent bitterness in your heart is to regularly pray for people who have done bad things or hurt you. That's easy to say but hard to do. We are commanded by God to forgive. 
It's mandatory to do and can be done in the power of the Holy Spirit, 
see time 6:40–7:39 in LIVE Q&A with Pastor Paul. Jesus forgave those who tortured and crucified him, even though they never asked for forgiveness (Luke 23:34), 
see The Crucifixion of Jesus. Stephen forgave those who stoned him to death 
(Acts 7:55–60). We must forgive unconditionally, however wrongly they have acted towards us. We must try to forgive our fellow human beings in the same way that God forgives us. If we don't forgive, we leave room for bitterness, something that spreads like a disease (Heb 12:15).

However, that doesn't mean we have to accept abuse. We can act to bring about a change in a bad situation. But it's crucial that we forgive the people who have wronged us, in our hearts, even if they never ask for forgiveness. In movies, the hero usually acts against an injustice by taking revenge on the person. It's not biblical. One should act to bring about a change, but not through revenge, see "Love and not revenge" in The Sermon on the Mount. Paul explains this very well in Rom 12:19–21, see also Proverbs 25:21–22. 

If you are at the end of your life and are aware that you have unforgiveness in your heart, you must forgive these people in your hart in prayer to God before you die. 

See also Whose Sin can We Forgive? and Dealing With Sin in the Church.

See also Some stories in the gospels at the end of The Four Gospels.