I feel similar. I already have one parent gone, my grandparents will be going soon, and my other parent is older for being a parent so I'll still be young when I lose them.
I also have BPD and major abandonment and attachment issues so it literally almost kills me on the rare occasion I connect with someone and love them too much (I only idealise and then grieve, I don't personally switch to devaluing) and then they abandon me. People say it "hurts" when someone they love leaves them. For me I end up basically purging my whole soul and regressing into my childhood abandonment trauma.
And then there's the guilt I feel about leaving my family behind because I'm young (well, I'm 25, some people may not say that is young lol but I do) and I get images of them crying and devastated. But in reality I can't live the way I am. I don't fit in with this world. I've completely become intolerant to distress, which I would say is understandable because I've experienced enough distress for a lifetime, so I can appreciate how people become intolerant to distress, and it makes me cringe when professionals focus on "distress tolerance" with people. I believe our souls basically become exhausted after so much of it.
Anyway, sorry for rambling.
And I'm sorry you're in this position Squiddy.