Elle - he is going to kill you.
You know this, right?
a hand around the neck is an immediate rocket ride up to seriously dangerous man when it comes to risk assessment.
You know this is not right, you know this is abuse.
You do know these things escalate? never ever getting any better, only worse and worse. This man could change ANY TIME HE WANTS TO. But he doesn't want to, because he LIKES HURTING YOU AND YOUR CHILD.
You are well on your way to becoming a statistic. 2 women a week are killed by their partners.
The next time I hear about a woman being killed by her partner, and her leaving behind an 8/9 yo, I will wonder if that is you. One day it probably will be.
If you can't get out and are happy for your child to grow up without a mother etc, by all means - that REALLY IS YOUR CHOICE.
Your son however has no choice in this and you are allowing him to be abused by not dealing with this situation.
If you can't demand more for yourself, demand better for him. If you can't put your DS safety and future first, please give him to his father?
Or to me, I'll have him. Anywhere but where you both are now. If you can't stop this for him, give him to anyone but you.
That is how seriously you need to take it. Act now before your DS says something or does something in school that alerts the SS and they will be forced to do something to protect him if you can't.