Selena Gomez Dumps Jenner Girls -- I Have Enough Toxic People in My Life

Selena Gomez has turned her back on former BFFs Kendall and Kylie Jenner because she wants to focus on what's really important -- MUSIC -- and thinks the Jenners are nothing but a toxic distraction ... sources tell TMZ.

Sources close to Selena tell us, the singer had an epiphany after Coachella last week -- where she was surrounded by booze and drugs while hanging with the Jenner girls, Justin Bieber ... and all the hangers-on that come with them.

We're told Selena's sick of that scene -- so she's decided to cut out what she considers the biggest sources of negativity ... Jenner girls included.

Selena made the cut official, and public ... by unfollowing Kendall and Kylie on Instagram. She also deleted all her Coachella selfies with the sisters.

The Insta-purge continued ... with Bieber and a bunch of others getting dropped -- and, in fact, she's currently following ZERO people.

We're told Selena is determined to stay on the straight and narrow -- focusing on music and, get this ... going to church almost daily.

Makes ya think ... must've been one helluva party at Coachella.