Hello @Fishballsambz and welcome to our forum family.
I know what you mean about feeling anger, hurt and range. I think being a family member is so hard as your Mum can probably make her own decisions, which you might not agree with and you are powerless over this and being able to make her better
This might mean a role reversal which might be difficult for both of you.
Perhaps you have personal commitments that you might have to reconsider and it curtails your lifestyle and quality of you life.
How to be an effective caregiver is your question and I think that depends on both your needs and relationship with each other.
There are emotional and practical needs for both of you and it might mean spending quality time together or shopping, cleaning, cooking, gardening, travelling to appointments or visiting in hospital, etc I think it might be a matter of offering and doing.
It might be a thankless task and nobody asks how the carer is.
I attach the link to the Blood Cancer UK website details on Multiple Myeloma and being a family member
[Myeloma | Blood Cancer UK](https://bloodcancer.org.uk/understanding-blood-My friend or family member has blood cancer | Blood Cancer UKcancer/myeloma/)
I felt I needed help which I got through my GP and talking therapy to say how it really was for me and my feelings.
Personally it is so important to look after yourself as well.
Our forum and the Blood Cancer UK support line on 0808 2080 888 are both there for you to say how it really is for you
Be kind to yourself and please do keep posting