So sorry, Dawn. It is hard when something seems to come out of the blue like that and you didn't get a chance to say goodbye, but on the other hand it sounds like your mum didn't suffer and had instead been enjoying time away. If you have to go, this must be one of the better ways. Nothing ever really prepares those left behind for the shock though.
I am not at all surprised that all you can do is cry. I must have cried buckets when I lost my mum. I don't think there is any worse kind of loss than losing your mum. Mums are so very special and we have no other relationship like it. All you can do is remember the good times and be thankful for the time you were able to spend with her. She will always be in your heart, so you will never really lose her. You will hear what she would say when you are thinking about something, even something small and you will smile when something reminds you of her. The grief will ease eventually, but never fade completely. You just learn to accept it and live with it, but getting to that point can take a very long time.
Your loss is still very recent, so all you can do for now is try to remember to eat and drink properly and just take it one hour or one day at a time. It does get better. You will have bad days, but you will find that slowly, you also have better ones. I found having flowers around helped me. Also walking in the park. It is a calming place to sit and think and try to come to terms with all that has happened. It also helped to put together an album of favourite pictures of my mum and some people start a memory book or a memory box and fill it with items of special significance to their relationship with the person they have lost. It also helps to write down each day how you are feeling and what you are thinking about. Then, later too, you can read back over it and see how far you have come. It also really helps to get out of the house and amongst people for a couple of hours a week. Grief is very draining and exhausting and it helps to have something else to focus on for a few hours, to distract you and give you a break from it a little. It stops you dwelling on it for a short time and I think that does you good.
Try to be kind to yourself, Dawn. Crying is sadly one of those things we do lots of when we are grieving, but you can do things to help yourself recover a little. You just have to find what works for you. A loss like that is huge and it changes so much. It changes you, your life, your future. You become this new person that you were not before and don't know how to deal with that, so you have to take it slowly and find your way into this new reality little by little, but find your way, you will. One day at a time, Dawn.
Sending you an understanding hug.