Hi Kate, what a terrible situation! This is definitely not what most carer's experience, which leads me to ask- Is your Mum on steroids as part of her treatment at all? These can sometimes effect people's moods and personalities (or some other drugs can too). You could have a chat with her GP and find out if any of her drugs could be effecting her moods and behaviour, then see if they can be changed/decreased/supplemented, for both your sakes. Otherwise I agree with Julie, that your Mum may need some help to learn to express herself more constructively. You definitely don't deserve this treatment, and if your Mum won't do anything about it then can I encourage you to look at getting some counselling support, as caring for someone is hard enough without being abused as well!
Warm hugs from Emily