i was in a verbally abusive relationship that did get physcially abusive on occasion, for 7 yrs. Sometimes i did push him, to see how far he would go, other times he lived up to his upbringing and copied what his dad did to his mum with little provocation from me.
We tried relate counselling, and individual counselling, as we both felt that we were each others 'big love' (still the love of my life even though i'm in a fantastically happy relationship & with the most fab bloke who treats me like a queen whom i adore), but it didnt really help us and just highlighted how faulty our relationship was.
In the end, i called off our wedding because i felt that we were destroying each other and making each other desperately unhappy. I am really glad i did, because i have never been happier, even though it took me years to work up the guts to do it. However, there were no children involved.
My point is, that if you are in a similar situation, you can talk to as many people as you like & get as many opinions as you like, but ultimately you need to follow your gut. If it tells you that you and your son & your partner would ALL be happier apart, then that's what you need to do.
If you feel you can make a go of it for your all your sakes, as well as for your sons sake, then thats what you need to do.
However, it isn't fair to expose him to any violence or bullying, either verbal OR physical, so if you are going to stay together, you need to be adult, resolve the explosiveness of your relationship and work at setting a good example for your son's future relationships. The best example for your son will be 2 parents who love each other and work together to resolve their issues, or 2 parents who split amicably and work together to ensure their son is happy & settled.
Best of luck to you, whatever you decide. and sorry for the long post - is an issue close to my heart