Oh Sweetie, I am so sorry that you are having to go through this *hugs*
I got myself out of an emotionally abusive relationship about 4 years ago. Thankfully, I had never married the *******, so that made the leaving part easier. The biggest thing that I learned is that, while it is hard to abandon the life you are used to, eventually it will get much, much better. I was with my abusive boyfriend for about 4.5 years and I had always tolerated his mood swings and temper tantrums. Eventually, something just snapped in me and I had enough. I called my parents and they moved me out the next weekend. Please, though, when you go to get your stuff, do not go alone. Pack up whatever necessities that you need, communicate with your soon-to-be ex via email or text message and let him know that you will be returning to get the rest of your stuff at a later date.
On a side note, I do understand why your dad and his parents want you to try and work things out, but I don't think they understand the severity of the situation. If you wanted to try and discuss things with him rationally, I would recommend getting a mediator involving and seeing a couple's therapist.
Anyways, lots of hugs and good vibes are being sent your way! And stay strong, you do not deserve to be treated like an emotional punching bag!!