Naya Rivera who is no saint hates her, wrote about her in her book I believe
EDIT: found this in digital spy.
In her 2016 memoir, Sorry Not Sorry: Dreams, Mistakes and Growing Up, Rivera wrote: "We are both strong willed and competitive – not just with each other but with everyone – and that's not a good mixture.
"As Santana moved from a background character to one with bigger plot lines and more screen time. I think Rachel – erm, I mean Lea – didn't like sharing the spotlight.
"If I'd complained about anyone or anything, she'd assumed I was bitching about her. Soon, she started to ignore me, and eventually it got to the point where she didn't say a word to me for all of season 6."