To the original poster,
Welcome to pc!
Healing4me gave you wise words but it is up to you chew that advice.

Many people walk through life setting red lines/ boundaries/ deal breakers we tell ourselves but when the time comes and we are faced with walking away or staying it seems everything is negotiable.
Your self worth, trust, and values that make you, you.
Also consider what kind of male role model this man is setting for your son!
By now you know what you have with him, the deal breaker.

Concentrate on forgiving YOURSELF for allowing this db to change what is acceptable in your life. For shoving it in your face, this is not the one for you, you and son deserve better.
LEAVING someone you LOVE hurts, LOVE for yourself forgives with time.
Misery LOVES COMPANY and this man has too many issues that he must heal on his own.
Happiedasiy.
PS, take the advice from women who have lived this life/ or in similar shoes. This relationship when looking back on your life will be a short period of time that taught you many things.