There's an artist I know and can't stand. I really feel like telling him in front of friends and family that his art sucks and that he's amounted to nothing.
You can't be serious. Why would you want to do this in front of other people?
Because I hate him. He is the biggest loser I have ever met.
If you don't like him why don't you just stay away from him? It's wrong to insult him especially in front of others. You're unnecessarily trying to create a scene.
I just want to see the look on his face when he hears it.
I think you're grossly overestimating how embarrassing this would be for him and underestimating how embarrassing it would be for you. You are much more likely to keep your reputation intact just ignoring the guy.