my manager favors people and is dating a coworker.

At my work It Is semi awkward because the manager and employees are somewhat friends and I feel as If I have to be nice to everyone because If I do not they will cut my hours. also my manager Is In a physical relationship with my coworker whom Is a minor (17) and he also gives her special treatment such as not making her work as diligently and slacking in maintaining a professional work environment by fraternizing at the work place. I recently found out from 2 coworkers that my manager was talking Ill-fully about myself and saying he might fire me. when I found out, I decided to confront him the next day due to the fact that I do not slack in my work and maintain my professionalism at all times, I went to the work place and asked him about the situation and I felt as If he was not taking the matter seriously because he spent his time on the computer and not talking to me while making eye contact, therefore I felt as If he was lying to me even more not wanting to admit he might have said something out of anger by mistake. when I left he continued to text me saying It was not true and offering to hang out or do stuff together with him and others from work, I did not reply. Since the “discussion” he does not acknowledge my presence at work and does not make any eye contact what so ever being sure to only talk to me through text when he needs me to go to work sooner than scheduled. Finally, yesterday my father called me to Inform me that there was a post on my Face book from my manger Involving a truth game, It asked If he thought I looked good In tights with a picture of an overweight person In tights. I called my manager about this new situation and the conversation just enraged me so I yelled and hung up, he continued to text me even after I had said not to unless It was work related, my father got In contact with the general manager and now today we are having a meeting, my father Is concerned the GM will not show, because of my own conversation with him that we had after my shift was over. I had called my GM to Inform him of the relationship between my coworker and how It made me feel uncomfortable and I also mentioned the poor work ethics at my work place. now we are disputing whether or not to bring this matter to a legal attorney for a case, because If my manger and the coworker worked last night as scheduled It Is wrong because they should be suspended for the accusations. what should I do?