I'm in love with my cousin
Do you mean that? Why would you be in love with your cousin?
I love her to bits, I'd do anything for her
It's not good to be in love with a relative. This is called incest which is immoral and illegal.
I'm going to marry her no matter what.
You should never want to marry your cousin, that's immoral. You need to go and find yourself another crush that isn't your family.