My sisters and cousins from extended family is ignoring me. Should I feel relief that I don't have to talk to them?

depends on if it is hurting you not talking to them. if you don't care then let it be and be relieved.

I ignore mine. I don't even follow them. I don't know if they're aware of it but it has been many years since I've seen them. I don't think I owe them a follow.

Yes