A will has been submitted this morning to the wizengamot. Here's what we know:
1. Your Aunt Ermenegilda submitted it.
2. Her son is the alternate beneficiary
3. She claims that he was aware of where the will was and he had not told her until recently with an owl after his escape.
4. Inheritance law doesn't care that he's an escaped convict. He can still inherit.
5. The will requires you to marry a pureblood with proper pedigree. The last name must be on of the Sacred 28. There must be no known Muggles in the lineage.
What we can do:
1. I put a response fighting the will, because it's untimely and we can't prove that it's not original since I doubt your cousin would want to come in and testify. There are magical ways to prove it, though. This could go either way.
2. You reach an agreement with your aunt.
3. You get married.
We have thirty days from today to pick one of these options.
I should add that wills are public, so people will find out.