My moms dying and Im not there to help and feel guilty doing everyday things.

My mother has become mentally sick in the past couple months and it breaks my heart as she has changed into a complteley different person these past few weeks. I live in another country and my work doesn't give me time off. She isn't eating or drinking and hardly speaks to me. When I try and talk to her over the phone she just speaks for maybe a few minutes and tells me not to worry about her. If anything ever happened to her I think I would honestly not be able to handle the pain and stress. She is my best friend and I love her more then anything. I am now hardly eating,speaking to my friends or doing anything except laying in bed. I feel like its my fault she got worse when I went away and I wasn't there like she was there for me for 28 years when I needed her. Should I quit my job and go help her? I feel beyond guilty doing things in my everyday life because she cant anymore so I try not to enjoy myself and not go to work. I cant cope with her not being herself and I ask myself why and blame myself. Im 13 hour plane ride away from home and it eats me alive knowing she might pass before I see her. Please help !!!