You do not need a counseller
or a shrink
or a doctor
or anything like that.
And the reason your mother wants you to get on with it is because if it came out then it would make her look bad for not doing anything about it when it was happening, irrespective of if she actually knew or not, that is just the way the world works.
The fact that you are admitting something as dreadful as this has happened to you and you are admitting it in public (although you are still relatively hidden behing your screen) means that you are nearly half way to exorcising the demons within yourself.
As probably most others have said, what happened to you was in no way your own fault, although it is something you have had to deal with.
Perhaps you have a really close friend that you could discuss this with or perhaps you feel that they would think less of you if you did.
It is definetly a tricky situation.
My only true advice to you would be to consider and ask yourself what way you think you can work this out. I am not saying you have to deal with something like this solely on your own, but what I mean is ask yourself, do you say to so and so or to somebody else. do you tell them everything or hold back on some stuff.
You also mention about something like this going on your medical record, well I am pretty sure that this would never happen.
What you may want to consider is maybe speaking to your doctor or gp and ask for some advice, they may well be able to point you in the correct direction.
But remember the final decision on how you handle this has to come from yourself, it is the only way that you can truly solve it.
I hope you all the best and hope everything works out for you.