This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
悷 combines the heart radical 忄 with 戾, which likely contributes both sound and a sense of twisting or perversity. The exact historical development is uncertain.
The heart radical 忄 beside 戾 suggests a twisted or distressed heart, which fits the kun reading かな.しむ (to grieve).
For レイ, imagine a ray of light piercing a grieving heart: ray -> レイ, and the heart 忄 feels the sadness.