India didn't betray Kashmir. The king of Kashmir (Hari Singh) was a Hindu and wanted Kashmir to be an independent country. But Pakistan wanted Kashmir, so it funded insurgents against Kashmir. When the Kashmir king couldn't face them, he sought India's military help. India agreed on the condition that Kashmir should be annexed to India.
The UN resolution says that India should conduct a free and fair election in the entire Kashmir to know what Kashmiris want (self determination). But for that, Pakistan should surrender its Pakistan-Administered-Kashmir to India and China should surrender Aksai Chin (if it has any population).
Obsession with Kashmir is burning Pakistan more than India.