If you literally just married her because you wanted children then divorce her i suppose.
But to me marriage is not for kids, its about being committed to someone whom you love, and I would never divorce anyone if I found out they were infertile. I married them because I love them and wouldnt just get rid because they arent fertile, they cant exactly help that fact (most of the time).
Adoption is a great gift for people to give, so I would go down this route rather than penalise my partner, they probably already feel upset about it because if your trying for children or talk about it they obviously want kids of their own, imagine how it must feel to not be able to have that and then have your partner leave you for it to.