If you want to know how to hide your feelings from everyone so they won't see it in you,- that's very difficult, in Proverbs 28:19 The Bible tells us:

19. As in water face reflect face, so a man's heart reveals the man.

I believe this means that no matter how you feel inside yourself(heart), people will see right through you. That means if you have joy in your heart, then you will show joy, but if you feel anger in your heart, you will show anger to others.

Pray today to The Lord to give you joy in your heart today.