My dad is being a jerk and I need help

I'm 16 and my sister is 18 she is graduating tomorrow and I'm upset because I won't be there. I got covid for the 3rd time. I was really looking forward to seeing her graduate. I'm not a bitch and I don't like hurting people's feeling, but my dad is making this harder for me than it needs to be. He won't allow any member of my family to stay home with me so I can have some company and it's really upsetting and I feel alone. I can't go to the graduation because that's the right thing to do even if I'm feeling fine.