This is so raw and you can tell the narrator is deeply in love.
The only critique I have is, youre using the extended metaphor of cancer, but you use the line "id let her consume me, even if it meant risking my life."
If the love is like cancer, cancer = a risk to life.
So saying "even if it meant risking my life" is a bit long winded.
Perhaps write
I'd let her consume me,
Even if it meant dying
And maybe then,
My ghost would be content.