Then don't face it.
2 years ago I was signed off with stress because of bullying by my old boss. I would go to sleep crying and would cry in my sleep. The thought of going to work made me physically sick. This amount of stress can affect you physically as well as emotionally, I had 7 periods in 9 weeks. I would shake, I didn't want to go out, I was literally a wreck. I was referred to counselling by my doctor and whilst in with her I was in such a bad state she called in 2 doctors to sedate me.
You have everything written down and you have been threatened with physical violence. You don't really need a witness to this to be honest, the doctor would know the truth just by listening to you.
Ring your doctor now, or your midwife and tell them everything hun, and stress the point that you have been threatened. Please don't let yourself get into the same state I did, it very nearly ruined my entire life and you have baby to think about too.
Speak to ACAS for free advice but only when you feel able to go through this without getting into a state. Your employer has the obligation of Duty of Care towards you and they are failing in this.
Please don't go in and suffer the way I did. I am welling up now just thinking about it, it takes a hell of a long time to get over.
Much love to you hun, feel free to pm me if you need to get stuff off your chest xxxxxxxx