I believe there are two different types of forgiveness.
One is for yourself, the other is in relationships.
The one is for yourself.
And forgive us our debts, As we forgive our debtors. Matthew 6:11 New King James Version
If someone does you wrong, you are to forgive them for yourself.
If you do not forgive them you will become angry, bitter and full of self pity. That causes all kinds of physical and spiritual sickness. And, worst of all, if you refuse to repent it will badly affect your relationship with Jehovah. You will end up all alone and bitter. Each day will seem like a living Hell. I have seen a lot of that in seniors homes and i n the lives of many I knew as a child that are now adults.
The other is relationship.
Moreover if your brother sins against you, go and tell him his fault between you and him alone. If he hears you, you have gained your brother. But if he will not hear, take with you one or two more, that ‘by the mouth of two or three witnesses every word may be established.’ And if he refuses to hear them, tell it to the church. But if he refuses even to hear the church, let him be to you like a heathen and a tax collector. Matthew 18:15-17 New King James Version
Now in the time that Jesus said that Jews were forbidden from having anything to do with a heathen or tax collector.
If someone is abusive to you are refuses to repent (repent means to admit what you did, admit it was wrong, to say you are sorry, and to stop committing the abuse. Many times that will mean going in for Christian counselling) do not continue in the relationship. If a spouse gets drunk and beats up the other spouse (and yes, women do it to men almost as much as men do it to women) and refuses to stop do you really believe Jesus wants you at continue on in that relationship? Not the Jesus I know and love.
The reason you take two or more witnesses is so the offender cannot say you did not try to reconcile with them or that it never happened (I have personally experienced a lot of that one).
Now many of us do not attend churches but we can go to Christian councilors and if available in your area go to group sessions. If the offender refuses it is because they know they are wrong but the relationship is not important enough for them to reconcile. If it is not important enough for them then why should it be important to you?
May I suggest, if you live in North America, to look up Focus on the Family for help and online resources. RBC.org (go to topics and you will find many exhalent booklets to help you) as is acts.org.
Prayer: Please Jehovah Kal El (voice of God) bless me with discernment to know when and how to forgive others as You do. I humbly request this in the name of our Supreme Judge Jesus Christ. Amen.
May the sunshine of Jesus’ sweet love bless you today and every day.