Jesus teaches about loving other's in Bible Mathew 5:43-48 "You have heard that it was said, 'Love your friends, hate your enemies. But now I tell you: Love your enemies and pray for those who persecute you, so that you may become the sons of your Father in heaven. For he makes his sun to shine on bad and good people alike, and gives rain to those who do good and to those who do evil. Why should God reward you if you love only the people who love you Even the tax collectors do that! And if you speak only to your friends, have you done anything out of the ordinary? Even the pagans do that! You must be perfect - just as your Father in heaven is perfect! Mathew 5:43-48
So when Jesus teaches us to love our enemy how much more important is it to love our patents, brothers and sisters, in-laws & relatives even though they have done some thing wrong against us.
How can we forgive and forget the mental pains?
Yes it's very tough to forgive others mainly close relatives and then live with them as if nothing has happened when they have wounded us with words and deeds. Jesus does not teach things that are impossible. Jesus has lived what He has taught us. So to obey the will of God there is always a way just ask the Lord to help you to forgive your enemy and to love your enemy. When you take the first step to honor the word of God He will surely make a way out for you. What a Joy or union and relationship it will be on the day when your enemy returns to you whole heartedly to love you, God will make this happen else He will make a way out for you.