Two hearts collide

Over the next two days I was panicking. I didn't want what happen to happen. Was this real? I didn't know. I was sad and confused. I was being hurt.
During gym on Monday, I began to cry so the teacher sent me to guidance.
" You okay, Megan" Ms.Smith asked.
"no" I said, the I told her about Greg's illness. We talked for over an hour, then she handed me a notebook.
"Write down in it every day," Ms Smith told me.
Later that night I wrote my feelings out. Then another call came. It was confirmed that Greg had cancer. I visited him later that week.
"Hey," I said. I soon found out that Greg didn't want to be diagnosed, but it just happened. But I didn't want to hear that. We got into a huge fight and I left. I couldn't stop crying.
Soon he called and said that he didn't want to break up with me. I was the first girl he ever loved, and he didn't want to lose me. I don't know what to think anymore. This is getting too pathetic. What should I do?
Weeks later they told me that the only cure would be a marrow transplant, and they would be looking for possible matches. Could that save him? After his parents tested (they weren't matches), they begged me to take the test. I took it and I was surprised that I was a match.
Maybe I can save his life.