Only child and death of a parental figure

In August my 92 year old grandad passed suddenly. Myself and my mum had been living with him for around 20 years. He had always been like a father to me. We were there at the very end all the way through not daring to leave his side. It was traumatic but we got through it.

My mum has 2 brothers that never did much for my grandad. We found that they stole the will before he died – which left everything to me and my mum.

We don’t care about the money as we’ve never been well off but I feel awful that my grandad’s sons have stole from him and stopped his last wishes playing out.

My mother is on benefits due to long term sickness so the money would have meant she would be set for life. There wasn’t much but enough for her not to worry about turning on tv and lights as she is now.

I feel calm and like I’m coping most of the time. I moved out during my grandad being in hospital and now feel settled finally. However I have these sudden bursts of anxiety as I know it’s just me and my mum now – no other family as they have disappeared. I feel so responsible for making sure she’s ok and at the same time dreading the same thing happening to her and having to watch her last breath.

Anybody have any tips on how to deal with situations like this becoming overwhelming?