Blake Lively scored a massive victory against Justin Baldoni in her “It Ends With Us” legal war … and she’s feeling pretty damn fantastic about it, TMZ has learned.

A source close to Blake tells TMZ … the actress was feeling “grateful, vindicated and relieved” after the judge threw out the lawsuit filed by Baldoni and Wayfarer Studios on Monday morning.

We’re told Blake’s proud she stood strong and used her voice … and thankful the judge saw through the other side’s charade … and ruled Justin’s counterclaims can’t be used as retaliation.

As you know … Justin and Wayfarer sued Blake and Ryan Reynolds for $400 million and the New York Times for $250 million, alleging defamation over an article about all the drama on the “It Ends With Us” movie set … a story Baldoni alleged was a part of a smear campaign against him.

The judge based his opinion on the finding that Lively had included her allegations in a civil rights complaint, and therefore she could not be held liable for the claims … and the NYT fairly relied upon that complaint as the basis of their story.