And were you happy on your holiday?

As you know, Simchat Torah is a holiday in which people are supposed to be very happy (literally, the word Simcha is in the name of the holiday).
In addition, it is one of those in which they say “the time of our joy”
 
The question is, how much and how can we be happy, and should we even be happy when what happened at this time last year happened?
And in general, how can we rejoice in the holiday of Sukkot, etc., with full joy when we are still in the middle of all this?
Is the Torah’s expectation that we be in dissonance? Perhaps relative joy? How should we generally behave in this situation?
 
Thank you very much!