My partner didn't give a speech at his best friend's wedding so I'm thinking that I'll call him an asshole.
Why do you think he is an asshole?
Because he should've done it. It was his job as the best man.
Perhaps he's just a bad public speaker? You should refrain from calling people bad names. It makes you look small.
I'm angry that my wife made me look bad in public.
While you're upset and that's understandable, not everyone is good at oral speaking. You should be supportive of your wife and not put her down for something that was most likely difficult for her.