Grandfather Died, His Wife Kept It A Secret And Is Trying To Take My Inheritance

Location: ohio/mississippi

My grandfather died febuary 15th, but my dad and I didnt find out until 2 days ago. He hadn't talked to my grandfather in 2 years, so when he tried reaching out again and was met with silence he did a wellness check and thats how we found out. His 2nd wife was always abusive to him and she kept his death a secret and is still living in the house that I was supposed to inherit. The house is in Mississippi as thats where my relatives live I moved to Ohio years ago so im not sure what all I can do. Im young and not that familiar with the legal system, but i am struggling financially and would like the money and property that was supposed to go to me. My grandfather also had dementia. My dad went to see him when he was still alive and he didnt remember my dad or even me when my dad tried to tell him about me. There's a chance she changed the will while he was in his dementia state which I know is not legal, but like im not sure if I have to prove that. My dad is homeless in mississippi, has been arrested multiple times for drug related charges, and doesnt have much. He hasn't had any luck with reaching out to a lawyer because of this. He's doing what he can so I can have what's supposed to be mine. There was no funeral or obituary. He was cremated and buried with the rest of my relatives on that side. I spent a lot of time with him as a kid so this really hurts.

I'm planning on reaching out to a lawyer soon. I've never contacted a lawyer before. Would I be able to get my inheritance back when I know so little about him and am in a different state? I feel helpless with what little experience I have with the legal system and with what little I know about my own family all because of that one woman. What kind of information do I need to prove that my inheritance is supposed to go to me? Can she get in trouble for keeping my grandfather's death a secret from his own grandchild and only son? Basically, what all can I do in this circumstance? I always planned on selling that house once I inherited it as that was promised to me for my whole life.