I don't know if you are doing anything to make him angry or not, but he is always responsible for how he responds.
We all have the ability to walk away from a situation that is upsetting us, or when we feel like we are losing control. Even with PTSD, your ex has the same ability. PTSD may make it more challenging for him to recognize it, but if he's been in counseling for a year, I'm sure he has tools to deal with stressors.
That said, he's your ex, and he has threatened you with physical violence. Maybe for both your sakes, it's time to leave each other alone. It seems like a must for your safety, and he needs time to heal. It doesn't mean you don't care about each other, but sometimes, being apart is just healthier for all involved.
I'm sorry. I'm sure it hasn't been easy.