Father's funeral

Okay so I'm 18 years old. I grew up with my mom and my three siblings. They are all older. My mother was an alcoholic and so was my father. My father hasn't really ever been in my life. I met him a maximum of probably five times. I think i met him around maybe age 14/15. But there is times he tried keeping in contact with me. He would call me and talk forever. During this time my mom was in jail. But once she got out i stopped answering his calls for some reason. He tried seeing me. One year he came up here and he got me stuff for my birthday. (He lived about 30-40 minute drive away.) Him and my mother got divorced years upon years ago. He was very physically abusive to her. Well he recently just died. Me and my other brother decided we want to go to the funeral. And now my mom is getting mad because me and my brother are choosing to go to the funeral. We want to meet our family that we never met. Aunts, uncles, cousins, etc. Part of me wonders if she kept us away from our dad. Because my brother told me he remembers he came to see us and she wouldn't let him in when we were young. I understand she had her problems with my father, but i don't agree she should have kept us away from him if that was her intention. I feel like i will never know the real answer. My mom and her side of the family are emotionally abusive, unstable, etc. So i couldn't straight out ask her and get a real answer. I feel as if there are so many questions left unsaid to my father. But are we wrong for going to the funeral?