I believe I was discriminated against at work, what do I need to prove this?

I filed a complaint against a co worker in September, it was during my 90 day probation. A meeting was set up between my manager, the other employees manager, myself and the VP of member services. I requested not to attend meeting based on the fact my complaint was about over hearing the employee threaten me physically. The VP stated she did an investigation in one day and could no prove what happened either way. During the meeting the employee did admit to approaching me physically at work which I precived in a threatening manner and he apologized. We were sent back to our departments. During this time I asked my manager if she was happy with my work and she stated yes and at my 90 day evaluation would request more money for me. Other employees got involved in the incident, they belonged to the other employees department. They would not transfer calls to me properly or would leave out information when transferring members or clients. Some clients even complained leading to e-mails being sent explaining how the phone calls should take place and still there was no change. I started to see my manager was allowing calls to only be transferred to her. In November another manager received a call that should have went to me and when she asked my manager why calls were still not being transferred properly my manager stated that they were uncomfortable transferring calls to me, when I asked why she shrugged her shoulders. That evening I sent my manager an e-mail requesting a meeting to discuss how the other department could feel comfortable sending calls to me and her suggestion was to put myself out there more, although on several occasions I would speak to these employees and be ignored. During that time another manager who works above my manager asked me to go in and edit, close out cases that my manager did not do correctly. There are documented e mails stating how good of a job I was doing. I had the meeting with my manager Nov. 16th to discuss how to build a better relationship with the other department since the incident in September and was fired on Nov. 19th. It states on my seperation letter did not meet job requirements. I was never given any negative feedback regarding my work, it was a complete shock to me. I was told at the termination meeting the reason I was being fired was becsuse it just was not working out. My manager also stated that I had not handed in a pto form from a day I left early which I had and was already paid for in my previous check but it was taken out of my last check. I also have e mails from the office manager listing specific individuals who were instrumental in having me fired.