I can understand your hesitation about going to the police. It is much easier for people to tell you to go to the police about it, but it's not them who have to live with the aftermath of that decision. However, the result is probably not as bad as you think. Many people have clouded views of the police and what they do, but if you went to see them and explained what was happening and your fears, the chances are, they would agree to talk to him and officially warn him. So, he would know that if he physically abused you again, he would be officially charged. You would hopefully find that the official warning, or the caution, is enough.
An alternative would be to warn him yourself. Next time he goes to hit you, or you can sense it's about to happen, tell him that if he does, you will go to the police. Say you have been talking to friends and relatives and they have advised you what to do. The shock of hearing this, coupled with thinking about others talking about what he has been doing, may be enough to make him stop.
Obviously, I don't know him, only you know what he's like and how he reacts. Don't do anything that puts you in more danger of getting beaten worse. So, it has to be your decision how you go about this. But I do think, if it's the only way, that talking to the police should help. And if it results in you getting beaten less, it has to be a good thing.
If you are in the UK, call 0800 11 11 - childline can give some really good information, and it doesn't show up on the phone bill if you use a landline, so call them.
-------
The only good thing about breaking up
Is the making up we do after