Firstly, I'm so sorry for what you have been through, and the emotional trauma you continue to go through because of it. You have absolutely nothing to be ashamed of. I hope you are getting some professional support? If not, will you look into it? You deserve it, and sounds like you need it if you are carrying shame that you do not deserve to be carrying.
Secondly, my thoughts are rape victims should always report it. But life isn't always like the movies and justice isnt always served and it doesn't always work out for the best, and along the way it can being further emotional trauma.
Finally, if you report an offence to the police, they are under an obligation (due to home office rules) to record it. Once it is recorded, there is every chance, with something so serious, that it will be pursued, even if you do not wish to go ahead with it. It might not be, but it could be.
My advice is don't feel you have to make this decision immediately, it might need to be part of your healing process. Have you spoken to Women's Aid? They would be able to advise I'm sure.
The best of luck to you. Please seek out help. You deserve it xx