Hi Jad,
Like JarHed said, anger is common for vets with Combat PTSD, and they need to get help to manage that themselves. However, as a supporter, there are some things you can do to help yourself. Setting boundaries early and being consistent is essential.
When the verbal abuse starts, you just cannot engage him because it will be like throwing gasoline on a fire. If you sit and take it, then it will continue to a place that is not good for either of you. You need to set your boundary and stick to it. At the first instance of verbal abuse calmly say "I cannot listen to you talk to me like this. Call me when you calm down" (sometimes I will even put my hand up in a "stop" motion). Then leave. Take your son and leave the house. Go to a friend or family's place, go watch a movie, anything... just give him some space, and remove yourself as a target. Do not call or text him, let him calm down and contact you when he is ready.
This is a non-verbal way of enforcing your boundary. You will not tolerate verbal abuse (boundary), and if he starts yelling or lashing out, you will leave (consequence of crossing your boundary). Any problem or irritation that started the lashing out can be discussed later when you are both calm. Plus this is a safety thing. It's hard for things to escalate if you aren't there.
There is a great book called "The Post Traumatic Stress Disorder Relationship: How to Support Your Partner and Keep Your Relationship Healthy" by Diane England. It is a good starter book for supporters, especially those of us who love a combat vet with PTSD. It also has a great section on how to solve conflicts instead of arguing. In the military, they are trained to fight in "fight or flight" situations, and combat just enforces that training. It is not good to argue with them because of this, so there are better ways to talk through things.
Doing this has helped my relationship a lot. It sounds kind of cold and clinical, but it really does work. My vet and I call it "the business of dealing with his PTSD." I know that he doesn't want to be mean to me or hurt my feelings, and he knows that I love and support him 100%. It is just a matter of learning how to communicate and keep the stress levels down.