Clarebear27, love. You can't STAY in this.
For the very sake of your boy - who WILL grow up to treat YOU the way his dad does, treat HIS GF and wife the way you are being treated.
You are not being selfish saving your boy from growing up under this terrible influence. You are doing this for him, and for YOU.
please read the book Why Does He Do That by Lundy Bancroft, it'll really help you see what is going on and how you are not to blame for it.
In short your P is CHOOSING to treat you like this, because he WANTS to. Nothing you do, think, say or otherwise caused this, would ever cause this, or could ever STOP this happening.
No amount of negotiation, reasoning or pleading will stop this, it will NEVER get any better, only WORSE.
If the 27 in your name is your age, you have a life time ahead of you, believe me, you have the world at your feet.
What is your financial situation, could you go somewhere else? do you have friends/family that could help you?
Please leave this bully, I promise you that life will be so very much better without him. It may be hard to begin with, but it WILL get better. At least when you are out, you have HOPE. Staying in this relationship you are literally in a hopeless situation.