There isn’t an easy path to helping an abuser change. It would start with them having some very painful consequences for their behavior, in hopes that their motivation to stop repeating their abusive behavior would be enhanced. Then it would require a treatment plan specific to their own personality problems and history. This is where the failure of treatment typically happens. There is no motivation to put in extensive hard work as long as they have a strong tendency to externalize blame and hold others responsible for their behavior, rather than look at themselves. Often abusers have Cluster B personality disorders (if you’d like to do further reading, I’d look under that topic).