Have a google and find out where your local IDVA service is (Independent Domestic Violence Advocate). With a lot of them you can self refer and as the name says, they will advocate for you with SS, schools, police, courts, housing etc. if none of that seems applicable to you right now, just having someone on your side will be a massive help.
And you can keep him out btw. You can apply for a non molestation order based on what he's done.
You absolutely did the right thing in involving the police. If you do need to take this further and get legal then having some kind of evidence, the police, your call to WA etc. will all help in terms of getting legal aid.
And no, this isn't your fault and you didn't deserve it. It doesn't matter what you did, he chose to hit you. This is nothing to do with alcohol or anger management or anything else. There isn't any excuse for his behaviour, regardless of how he has spun it to you. Some people behave badly when they drink, some people drink so they can behave badly but none of it is a reason or justification.
And yes, the police were and often are shocking with DV cases. Which is why I'm saying to contact your local IDVA team. They know their stuff, can give you advice and they'll take you seriously and believe you.
Good luck. If you take nothing else from this post, please try and hold on to the fact that you didn't and don't deserve this (easier said than done, I know).