So I've been living a lie my whole life?

I don't know what to think anymore nor what to believe. About 2 weeks ago, my mom was arguing with a man. He had been coming before lately. The guy seemed mom's age and actually had a youthful face. I would guess he must be in his mid 30's years old but still looks 20ish. The man seemed extremely upset and at some point called mom bad names. Then I strongly resemble him, as if he was my male version and me his female twin, too much alike.

I couldn't stand it anymore and demanded why he was insulting mom. What the hell was going on. The man got emotional upon seeing me. Now everything seemed confused. Why is he yelling at mom? Why is he emotional suddenly? What happened is he found out about my existence not so long ago, did the test twice on two different clinics and it's positive. My mom admitted to lying about him abandoning us when she got pregnant. She always used to tell me the story that my father was her ex boyfriend that bailed on her, leaving her pregnant. What really happened is she never told him during the break-up, kept the pregnancy a secret, felt there was just no need for him to ever know, decided to raise me on her own and was hoping he never finds out. He did eventually and was very pissed off. They dated during HS and my mom had me at age 19. Not older than myself. I'm 17 now.

So I've been living a lie all these years? I don't know how to react actually. I really thought my father abandoned me and never wanted me.

Updates
+1 y
Now I'm wonder how many other men out there have been purposely denied fatherhood, denied from ever seeing their children, told lies about how the father abandoned them?
So I've been living a lie my whole life?
Post Opinion