General antonyms:
* Mourn: To express sorrow or grief.
* Sympathize: To feel or express sorrow or pity for someone else's misfortune.
* Console: To comfort someone who is distressed.
* Humble: To be modest or unassuming.
* Regret: To feel sorry or remorseful.
* Apologize: To express regret for something you have done.
Antonyms related to specific situations:
* Celebrate: To mark a happy occasion with a special event.
* Acknowledge: To recognize or admit something.
* Congratulate: To express praise or approval.
The best antonym for "gloat" will depend on the specific situation and the meaning you want to convey.