It is an absolutely normal reaction to feel angry in this kind of situation. You have perfectly good reasons to feel angry about what's happening to your mum. Of course you're angry on her behalf because she´s already been through a lot in her life.
But, it is also natural to feel angry about how all this affects you and your life. Your mum having cancer brings a lot of uncertainties to your life and a lot of changes to your normal routine. It makes you sad and worried when all you want is to feel happy and careless like most people your age would feel.
It can be hard to know where to direct the anger and we often find that we get angry with people who are close to us although we know that´s unfair and we don´t mean to do so. It is normal to get angry even with the parent who is ill and that makes people feel really guilty because the parent is of course not to blame. This can be a big problem - that because no-one is to blame for what´s happening, there is really no-one to get angry with. It is therefore easy to get angry with those around us and whom we feel close to, although they don´t deserve it.
It is also very normal that you just want to curl up and shut it all out. You know that is not possible, but it is important that you do try and escape from your worries now and then. It is very exhausting to be sad and worried all the time so try and give yourself breaks and do normal stuff with your friends which may distract you at times. Don´t escape all the time though - make sure you talk to people who are close to you about how you feel. The best thing is to try and get a balance between thinking and talking about your anger and worries but also get some breaks from it so that you are not being swamped by the difficult things that´s going on in your life right now. It might also be an idea to use the forum on the site and talk to other young people who are in a similar situation.
You are having a rough time, but you reactions are absolutely normal. I hope things get better soon. Take care!