While I voted for suicide in the first poll, I've changed my mind. Curtis was too narcissistic to kill himself. I'm changing to Taylor who was my backup choice. Her melt down and hospitalization are part of her manipulation.
Another fun filled chapter with a cliff hanger. Suicide or patricide by Taylor are my guesses, but Miranda cannot be ruled out either. Definitely not Jake or Travis, and I think it unlikely that Big did it.
Brad, Steff, and the rest of Will's family are also unlikely as they take time to plan things out before putting it in action.