This is an illustrated version of pllcrazyness’ amazing theory. I cannot help but look deeper into this, so I added some details. Enjoy :)
We know Ali likes to base her lies on the truth.
Note that I haven’t manipulated the part where “Ali” is hit in the head - in her flashback, she falls, but then we see the rock falling near her left foot and it looks like she is still standing. I don’t know if this is a production error of if this is supposed to be a hint that Ali was the attacker, or at least the attacker had her shoes.