I'm going to be fired tomorrow for exercising my first amendment right of freedom of speech, and I'm not sure how to tell my wife.
That's awful. How are  you going to get fired for exercising your first amendment rights?
I'm going to give up my job to protest against the first amendment restriction.
It's important to stand up for what you believe in, but you shouldn't keep your spouse in the dark about things. They deserve to know things that are going on in your life, especially important things like if you're going to lose your job. It's better to tell her ahead of time so she knows what to expect.
I'm not going to tell my wife. I'm sure she will understand. It's fine to maintain a healthy relationship with each other.
I think you are mistaken in not wanting to tell your wife. Your wife is your partner and is affected by the decisions you make in life. So before making important life decisions, you should consult with her about what you should do. It could lead to problems in your marriage if you do not consult your partner in all the big decisions.