Blake Lively is cleaning house after her brutal legal war with Justin Baldoni … cutting ties with longtime publicist Leslie Sloane after nearly two decades together.

Page Sixreports Blake dropped Sloane — who had been with her since the “Gossip Girl” days — months after Blake and Baldoni finally settled their scorched-earth “It Ends With Us” legal war.

Sloane wasn’t just watching the legal mess from the sidelines either … Baldoni’s $400 million lawsuit dragged her and her firm, Vision PR, directly into the fight … accusing them of taking part in a smear campaign against him. Those claims were later dismissed.

As TMZ previously reported, Blake and Justin settled in May just weeks before trial … with no money changing hands in the settlement.

We’d also reported there was plenty of behind-the-scenes drama in Blake’s camp leading up to the deal, including her bringing in powerhouse law firm Susman Godfrey.

The legal bills kept flying even after the truce … Blake later sought more than $8 million in fees and costs, but a judge ultimately awarded her about $400K.