Was I wrongfully terminated ? I was fired for

Was I wrongfully terminated ? I worked for a company as a general manager and was excelling fast. I was told I was the next for promotions and things were great. I got a call from my boss and was questioned in person about a situation regarding an employee with a female. It didn't matter I am happily married and it didn't happen. I thought this was a joke. I was told she didn't believe me and I was fired.
I called me wife and cried. I was fired and I didn't do anything wrong. I was told is was inappropriate behavior in the workplace. Didn't know what that meant. Days later I got texts and calls from multiple mgrs and co workers asking questions. Word got out I was fired for.... the sending pictures of my privates to a co-worker. They were telling me who was interviewed what was said and was the words were being exchanged between each other. Supposvily there was a witness, but didn't make sense if never happend.

My wife freaked out and went through phone records. Emails, history of computer. U name it... she wanted to know everything. Nothing came back with me speaking with the associate except her asking to switch a day off with another co-worker.
I had filed for a greivance to fight this bc this isn't true or right. I loved my job. I was told if I agree its true it will be a slap on wrist and get my job back. Well i agreed and it didn't work. My wife was even more mad.
She then messaged the girl and she said nothing happened. And she heard the same thing and was questioned but she said no and even offered her phone as proof. I called back to file again and told the person that I didn't do it and was advised wrong to get my job back. I want to keep fighting this bc I know I didn't do it and it's the principle. And now my name is ruined as a person who did wrongful things... and really hurt my marriage of 10 years. I'm feelin defeated and I'm not willing to give up.

I don't understand why I was let go if I said I didn't happen and she said it didn't happen either. If someone else called and complained but we both said no how could I have been terminated ? Is this defamation or slander ? Can I get my job back ? Please help me