How to control emotions?

I notice that when I'm 'not in the mood' I tend to be a lot more colder and human interaction is impossible or tough and unwanted, when I'm hyped I get enthusiastic and can engage properly, when I am hurt I can't hold my tears and emotions spur with lack of thought, therefor I appear weak, and when I get angry I become a ravage animal searching for blood.

I want to be able to control these feelings like when I'm not in the mood to be still able to react with enthusiasm or when I am hurt, to never shed a tear but gain confidence. I want to kill my emotions because I can't live with them in this world... not anymore.

I've also done some stage acting but that's totally different than the real world because in a scene you know what the follow of your actions will be, while in real life you can't forsee the outcome and be prepared for it. It frightens me.

How do I achieve this "coolness" in an unpredictable midst?