How Do I Claim My Inheritance?

My father recently passed, and it was brought to my attention that out of his five daughters, I was the only biological daughter (that has written proof that he is my father). The problem is that 4 of us were not with his wife, and the other that was within the marriage was adopted. I know that the laws stipulate that the adoptive daughter would have as much claim to his estate as I would, but I know that his wife is especially vindictive (she wouldn't let the family visit him in the hospital and will not allow most of his family to attend the funeral) and a snowball has a better chance in h#$^ than I do of her recognizing me as his daughter and helping me. I feel like now is the time to dot my Is and cross my Ts. Please help! Thanks!