I'm so sorry you are going through this. You'll be dealing with the shock of what has just happened, of being assaulted, with the anxiety and fear of what social services involvement is going to mean, and quite possibly with some grief - your relationship with your partner is not what you hoped for and dreamt of, and you'll grieve the loss of that.
So you might be feeling like you want to be in denial about what has happened, or to believe that it will never happen again.
Unfortunately the statistics are that men who do this, keep acting this way, and it keeps getting worse. Meanwhile your confidence and self esteem will be getting chipped away at, making it harder and harder for you to leave.
Can you speak to womens aid again? most areas have a 24 hour number. there will be someone there who can listen to you, give you some space to talk, and will have good advice if you are able to listen to it.
You are doing the right thing, putting your son first and looking to his and your own safety. Remember he needs a mum who is safe and well, if you aren't safe you can't look after him as well as you would do otherwise.
Also, not trying to freak you out more than you are already, and your hv and womens aid should have pointed this out to you already, but it is often the case that violence or controlling behaviour increases when a woman is trying to leave a relationship. This makes just now a more dangerous time - it fits a pattern that your partner got aggressive just when you were making changes in the relationship. So it is good to think through your own safety and reach out to people around you, or services if you don't have family / friends you can trust. The womens aid website has some good info on making a safety plan.
you sound strong and together, even if you might not feel that way! good luck.