I'm going to fake it with my wife
Why do you feel like you need to fake it?
My wife looks ugly and her performance is fucking horrible.
If you are no longer happy in your relationship, you should say something, and you can both find ways to reignite the spark. It's not good for a relationship to lie to your partner, and you will feel a lot better if you are honest.
I will break up with her if she gets mad.
It sounds like the problem may be a bit deeper than physical intimacy, so I have to emphasize that you should talk to your wife calmly and without judgment.  Remember how much you love her, and wanted to spend your life with her.  Don't throw that away without trying to improve things first.