Ilied about having cancer to my girlfriend. What do I do?

I've been with my girlfriend for about 2 years and about a month and a half ago I found out I had this lymph thing in my stomach that I had to get removed. I had to go to a bunch of doctor appointments to get ready for it and she knew bout the appointments but not what it was for. She didn't wanna know. So I had a really basic single insision surgery and got it removed. She asked about it and I told her that I still had a tumor in my brain. I didnt. About a week ago I told her it became cancerous and that I was getting another surgery to get rid of it today. She's away in another country so she doesn't have any way to contact me. She was quite sad and always crying because of it but I was to scared to tell her it was a lie even though it made me feel terrible. I was scared it would end verything with us and now the lie is almost done. When she gets back, I can tell her its all done but I feel terrible and I just don't know what to do. I know I dis such a stupid and retarded thing and I hurt the one person I cared the most about in my hole life. I don't know what to do. I feel so stupid and lost. I don't know why I did it. I can't even make up a reason. I just don't know what to do at all. I just need some help. Please can someone tell me what to do or just any form of advice. I feel so bad and I've even started having thoughts of killing myself because of it. I don't think she could ever forgive me and I just don't know what to do because I love her. Why did I even do this? Please can someone just tell me anything. Im so sorry ecause of it and I wantthia to all go away. What should I do?