Please consult your priest if you are having marital difficulty. Get a referral to a competent counselor. A breach of trust such as a secret sterilization needs counseling for both parties to help heal the harm done.
Actually, that isn’t clear at all.
I would suggest further study on the matter. I don’t think you can argue that at all. The Church is very specific in what it means regarding a permanent intention against children-- and I don’t think you can argue a woman who was twice pregnant trying to have a family had some sort of intention against children when vows were exchanged.
There aren’t any “grounds” for anything based strictly on what you’ve posted other than grounds to be angry at your spouse and hurt by their actions.
I would suggest you get some counseling.
You are putting the cart before the horse if you are still married. Get some counseling to heal the hurt on both sides.
If this is a hypothetical, well as with all hypotheticals on decrees of nullity-- there is no answer to be found here. Because with a decree of nullity EVERYTHING depends on the actual facts of the case.