Until one day he wasn't acting right
In the middle of the night, she checked his phone, Erica, right
The girl started noticing that her man was acting suspicious, so she checks his phone only to find the name of another woman.
The “Erica, right” is a double entendre:
The straight forward meaning is that the woman he’s presumably been seeing on the side’s name is Erica.
The subtler meaning is the play on words with ‘Erica Wright’ aka Erykah Badu who’s song ‘Tyrone’ is referenced later on in the verse.
To help improve the meaning of these lyrics, visit “Tammy's Song (Her Evils)” by Kendrick Lamar Lyrics and leave a comment on the lyrics box