I loved the concept behind this poem. It's true too often we say things in a fleeting moment and we don't realize what we're doing, it causes so many issues problems and we become someone we never were. Anger is a tricky thing.
I feel like in the second line something might be needed. It's correct but it just didn't sound right. I felt like we needed for while "they're" fleeting. I don't know, just leave it, it's just me I think lol.
I liked the reference to the 'you, you once before.' It's amazing how much we can change and become someone we're not and I found it interesting how you linked all of this to Medusa. Is it because of the idea that her eyes turn those to stone and you feel as though words turn those to stone, or feelings to stone? Medusa was beautiful before she was cursed so this concept works well with the ending.