I think that your thought is excellent to read about. (No "it.")
Not only do you not need "it" in the example sentence, but you should not use it. The sentence should be:
"¢ The event still hurts to think about.
Actually, the sentence could be improved in this way:
"¢ It still hurts to think about the event.
A passage from Practical English Usage* states:
Note that we do not put an object pronoun after the infinitive or preposition in these cases:
Cricket is not very interesting to watch.
(NOT Cricket is not very interesting to watch it.
She's nice to talk to.
(NOT She's nice to talk to her.
*Practical English Usage, Second Edition. Oxford University Press. 1995