How can I get rid of the habit of cursing that I've recently developed, and am I sinful for what I uttered previously?

Cursing is a bad habit and contrary to the ethics of believers, and "cursing a believer is like killing him." To remedy this, one should pray that Allah guides the person to the best of manners, remember the dangers of cursing, and that the curse returns with ill fortune upon its utterer if the cursed one does not deserve it. One should also frequently remember Allah, train oneself in patience and forgiveness, and replace cursing with the phrase "May Allah guide you." Additionally, one should repent and seek forgiveness for those who were cursed unjustly, and mention their good qualities.