Jesus gave a surprising command
Jesus spoke plainly to people living under Roman occupation, where enemies were not an abstract idea. He told his disciples to love those who opposed them and to pray for those who treated them badly. This is not natural, and Jesus never suggests that it is easy.
Praying for an enemy means you stop treating bitterness as your only response. You place that person before God, who sees both what they have done and what is happening in your heart. You might ask God to turn them from harm, show them truth, meet their real need, and bring them to repentance.
But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;
It is not a denial of wrong
Praying for someone does not call evil good. Paul tells believers not to repay evil with evil and not to take personal revenge, because judgement belongs to God (Romans 12:17-19). That leaves room to name what happened honestly and to ask God for justice.
David did this often. When violent people pursued him, he asked God to rescue him (Psalm 140:1). So a truthful prayer can include, “Keep me safe,” “Expose what is wrong,” or “Stop this person from hurting others.” If someone is abusing or threatening you, seeking distance, protection, and help is wise. You do not have to remain in harm's way to obey Jesus.
Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.
Start with honest, small prayers
You may not be ready to pray that an enemy prospers or becomes your friend. Start where you are. Tell God exactly how their actions affected you. Ask him to guard you from becoming cruel, bitter, or consumed by the injury. When fear is part of the story, the psalmist directs his fear towards trust in God (Psalm 56:3).
Then ask for one good thing that is fitting: that they would recognise their sin, receive mercy, choose what is right, or be prevented from causing further damage. Prayer may change your feelings over time, but its first purpose is faithfulness. You are handing the case to God rather than carrying the burden of payback alone.
Love seeks a different outcome
In Luke's account, Jesus connects praying for hostile people with doing them good and responding differently from the world around us (Luke 6:27-28). Christian love is not approval or passivity. It is a decision not to let another person's sin dictate your character.
Paul describes this kind of response as overcoming evil with good (Romans 12:20-21). Sometimes that may include a kind action. Sometimes the good and wise action is a firm boundary, a truthful report, or no contact at all. Pray for wisdom about the next step, and keep bringing the person and the situation back to God.
But I say unto you which hear, Love your enemies, do good to them which hate you, Bless them that curse you, and pray for them which despitefully use you.