Yeah I am Sunni and we fast (2 days) because of this reason. Regarding the Karbala incident, we stay neutral.
We do our regular work as usual.
Yes. There are many tragedies in our Islamic culture.. Many of sahaba and khalifas were killed and we do feel sorry for them.. but we can't mourn forever. We are forbidden from mourning the death of any person for more than 3 days.. that too without crying loudly.
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