It [Love] does not rejoice in unrighteousness, but rejoices with the truth; it keeps every confidence, it believes all things, hopes all things, endures all things.
1 Corinthians 13:6-7 (NASB)
The Ten Commandments can be summed up in two sentences, (1) love God and (2) love your neighbor. No one can claim to love his neighbor if he does not love God first. It is our love for God and our attachment to the law of His spirit that will teach us to love others as God Himself loves us, even to the point of giving His son as a sacrifice for the forgiveness of our sins.
When Paul tells us that love takes no pleasure in evil, he is indicating that not only should we not hurt others, but we should also not rejoice in their misfortunes, sufferings, or circumstances. On the contrary, when they suffer, even if they have hurt us, as Christians it is our duty to comfort them and help them as best we can. Jesus Christ, our example, gave us this command in His Sermont on the Mount: “Love your enemies, bless those who curse you, do good to those who hate you.
The law of love doesn't tell you not to be disappointed or to pretend not to be angry. He asks you to master this anger in order to express your resentments wisely. By doing this, you are not only protecting your siblings, but also your relationship with them. He asks you to be sincere and honest when you talk without trying to offend them. It's not easy, but you can start somewhere. The first step to this kind of love is to be led by the Holy Spirit.