@Nevergiveup28,
I understand how upsetting this is for you. But running to CWS may be not as helpful as you'd like it to be. You haven't said if you've had a conversation with your x about your daughter.
At 4, crying and defiant behavior kinda go hand in hand. She's developing normally and like all 4 yr olds, is demonstrating she can control some of her own circumstances. For example, she knew by telling you mommy slaps her would upset you. Did you talk to her mother about that? The situation at preschool is a perfect example. You daughter wasn't afraid the other child was going to get hurt if mommy slapped her - in fact, she most probably welcomed that thought. But she was scared about being tattled on.
It's normal.
Taking a nap is also another battleground 4 yr old can choose to exercise their independence. Being scared of monsters shows her cognitive development is right on track. A scary monster movie could be Monsters Inc, Scooby Doo or even Cookie Monster sings "C" is For Cookie. You seem to imply she's watching slasher movies with mom's full knowledge and approval. You might want to ask her mom about that.
You're not immune, either. Telling a 4 yr old that she would be responsible for someone's death for dropping a stuffed animal out of the car seems over the top to me. Does your car not come equipped with passenger window locks?? Use it, and put an end to that battle.
All in all, nothing you post does not seem like abuse in any way, shape or form. It does scream -- you do not communicate with your x whatsoever. There's your starting point, not CWS.