This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
懀 combines 忄 (heart/mind) with 會, which likely contributes the sound. The exact historical development is uncertain.
The heart radical 忄 beside 會 suggests an emotional state, but the specific meaning is obscure. Imagine a heart meeting something unexpected, causing a strong but unclear feeling.
For ワイ, imagine a heart 忄 meeting 會 and asking 'Why?' in a plaintive tone: Why -> ワイ.