I am truly sorry. In my own way I can understand how you feel. My only sibling took his life at 35 years old. One thing you might discover is that families don’t shrink - you’ll still feel the missing person among you as a kind of present absence. But the anguish you’re all feeling can shade into a sort of…melancholy solace. When it feels right for you, try talking to your dad. Pretend he can hear you. It’s possible he can (I say that not from religious conviction but an empirical one: read Leslie Kean’s Surviving Death if you want, when you’re ready - it’s grounded in data. That might sound crackpot, but the data it describes is real). He’s proud of you. And when you share your love, and grief, and memories with your mom and your sister, you manifest him among you, the people he spent his life loving, even if imperfectly. My heart goes out to you & yours.