OP, what I'm about to say comes from a place of kindness.
I've been where you are now (kind of). Years ago, I was with an abusive partner. I made excuses for him, I dropped domestic violence charges because I was too scared to leave, and I stayed with him because he convinced me I couldn't do better and that he would kill himself if I left him.
My family were devastated. They tried talking to me but I wouldn't listen. One day he strangled me, he grabbed me by the throat when we were arguing. It felt like forever, but in reality it took about 10 seconds for me to pass out. When I woke up he was still there. I managed to secretly call the police and they turned up and he was arrested. I was taken to hospital, where I underwent emergency surgery on my throat and the damage he had caused.
Even after that I was still unsure about leaving. My mum (a police officer who worked in the DV unit) was beside herself. Her colleagues were the ones who took my statement. They then did me the biggest favour in the world. They showed me photographs of women who had been killed by their 'partners', and they told me that it would be me if I didn't leave. Finally my eyes had been opened.
I left him that day, and started to rebuild my life. It wasn't easy, it took a long time, but I got free of him and it was the most freeing experience you will ever have.
Men like these don't love us, they target women who are weak and vulnerable so they can mould them into who they want us to be.
You have already lost custody of your son. If you don't take this step to get out now, you will likely lose your life and any self respect you have left.
You can do this. It won't feel like it now, but you can and you will do better. You will learn to love yourself again, you will become a strong independent woman, and most importantly you will be a great role model for your son.
Please don't wait until it's too late.