Is it normal: i have to fake feelings?

I feel like I have to fake sympathy for things I don't give a fuck about so I can be looked at as a nice guy, but when they say thank you it's really awkward and I wanna get away from them because I don't mean it. I can't seem to get words out of my mouth when I'm face to face with someone, even asking for a drink I dehydrate myself because I just can't get the words out even if I know they'll say yes, I feel like it would annoy them and they'd get mad. My blood pressure goes up and my heart races when I think about having to do something, like talking to someone I think, "Oh no I gotta talk to them idk how what do I do?" I end up going the other way because I assume the worst will happen. But through text I can be myself and tell people things I couldn't to their face, the only thing that overpowers my inability to talk is anger, in which I end up beating someone up because I can't tell them to shut up. Like a month ago since I'm quiet people walk all over me I got "Do you wanna get punched in the face?" out they said "Go ahead do something." and I starting beating the shit out of his face. Now I think I have PTSD because my heart races and blood pressure skyrockets thinking they now want me dead and they'll come kill me any minute, especially when I am trying to fall asleep I can't because my chest is pounding of fear. I suppose the worst fear I have is killing someone because I won't have a problem doing it, my adrenaline pumps just thinking about beating someone who's annoying me to death, but I don't wanna spend life in jail.