I'm going to give my friend's TV to his ex fiance.
Did he give you permission to do this?
No. I just don't like the way he treated her.
You may not like the way that your friend acted with his fiancee but taking his tv for his fiancee betrays your friendship with him. If you're not going to support him through the breakup, then simply stay out of his business and leave him alone.
I know it would make him so upset if I did it though.
If you know it would make him upset, that's the reason not to do it. Think about how he would feel to have you do this to him. He would be angry and frustrated and probably not want to talk to you anymore.