Diagnosed with melanoma

I had a flat black half a penny sized mole on my back which was removed a month ago. I wen t back for the results and was told I had skin cancer and that I needed to go back into hospital to have a further op! I'm still in shock I never thought it was something so serious! It's only a grade 1 but my life flashed by as I read that it was a serious cancer and can spread to your organs. Can anyone enlighten me? Still in shock as it just looked like an ordinary mole it was my sister who said to get it checked out.