Needs help, but doesn't need help?

Random one, bare with me. 

I work, can socialise (to an extent) - bare in mind all these things are a major struggle, but I do them. I live with mum and dad before he passed. 

I feel like, once mum passes (hopefully lots of years to come before that) - that I will inevitably struggle alone. I say this as when my mum goes out (be it, socialising, doctors - life etc) I just freeze, like a rabbit in headline and cannot cope. Is any one else like this? 

she's my best friend and safety net, and I am very scared for life alone in the future. 

does any one else feel this way? If so. How do you cope/how have you coped if You now live alone?