< The Pain of Loss: Why Nia's Death in Gurren Lagaan Broke Me
Okay, loads of things to address in this post, but first and foremost. Showing emotions is not weakness, it is not a strength either - it simply is who we are, emotional beings.
Showing, as you call it, an opposite emotion to what you're feeling might not be an accurate description. While I'm not familiar with the reference you mention, someone smiling at the time of someone's death may be due to relief, as a way to comfort the dying, or probably loads of other reasons.
What you seem to be struggling with is a warped emotional view, which is not uncommon at all. I myself grew up with an emotionally distant father, who only expressed anger or a stone face. I basically grew up hearing 'man up' twice daily and the first time my father broke down in tears, I was shocked for a solid hour.
Seeing a therapist might be a good idea. It can help you navigate emotions and might improve quality of life.