Hey, love. You know, I'm going to give you some advice here that conflicts with the advice you already received. Now, I have to be a little careful because I don't know the exact circumstances of this sexual abuse - you haven't said whether or not you consented, but by the very fact that you're calling it sexual abuse, I will assume that you didn't consent. Regardless of whether or not you were drinking, if someone has sex with you without your consent - or if you're incapable of giving consent (if you were too drunk, for example - then that is rape or sexual abuse, depending on what happened. If this is what happened to you then what happened IS wrong and is rape/sexual abuse. You didn't give your consent or were incapable of doing so through intoxication.
If you did give consent then, obviously, it wasn't sexual abuse. However, I'm going with the assumption that it was abuse as that's what you've called it here, yeah? :)
Now, as for telling your mother. Honestly? I think that was an incredibly brave thing to do. Talking about stuff like this is so very, very difficult and personal and, even though it's not worked out quite the way you wanted, I still think it was an awfully brave thing for you to have done. As for what to do now though, well, that's a tricky one. I think it'd be great if you DID go the the police, but I understand completely why you don't want to. I've been in this situation myself, and I understand that going to the police just isn't the answer (sometimes). If you're not ready, it's ok. You can't force yourself - you have to do what's right for you. Do think about it though, yeah?
Naturally, your mother is doing what her natural instincts are telling her to do - protect and get justice for you. I honestly think you need to have a good chat with her. I know it might be difficult, but you've come this far already, right? If you're not ready to go to the police and if you don't want your friend's parents called, all that stuff, your mum really needs to know, yeah? You need to recover and heal from this in your own time, and you can't rush into doing things that don't feel right for you.
I do think it's essential that you keep being so open though, yeah? Even if you don't think you can talk to your mum about things anymore, I do think it's important that you find someone to talk to. Sexual abuse is a very difficult thing to go through, even moreso if you're having to go through it all alone. Have a chat with your mum, yeah? Explain how you're feeling right now, how you're feeling about her going to the police and whatnot, and just let it out to her, hmm? Remember also that even if she DOES go to the police and you're not willing to talk, well, there's not much they can do without a statement from you, y'know? Let your mum know that you're just not ready to take it to the police. Acting out and suggesting the police was perhaps an instant reaction from her, and after a bit of time, she might actually listen to what you have to say.
Once again, I do understand how difficult this must be for you. Honestly though, nothing's going to be achieved here unless you have a chat with your mum yourself and explain where it is you're coming from and what it is you want to happen. By telling her about the abuse, well, it suggests to me that you were reaching out for someone... if that's the case, tell her that. Let her know that you just need her - her support, not the involvement of all these other people. And, once more, remember that there are people out there who can and will help you. Don't struggle on through this alone, hmm?
Take care. Feel free to make another eHelp anytime, or even join up to LiveWire and send me a message any time.