I Admit That I'm Scared

So, a bit of backstory.
I lost my mom 4yrs ago, and it was the worst time of my life, and I still struggle with it.

Back in late July, my father had a heartattack. The doctors told him his liver was also failing, and he wasn't going to make it.
I couldnt eat for a little over a month,and had to use all my power to just get up to take care of my pets.
Thankfully, he beat all odds.
Now, recently I found out hes doing horrible, and he cant do anything anymore.

Its so heartbreaking, i've went to see him everytime I could since the heartattack, and plan to again asap. (He lives really far away)

When I chatted with him a few days ago, he started telling me what I would receive after his death, and honestly its grim to think about, but I think we both know he won't be here much longer.

Mentally, im a disaster. I don't know how well i'll be able too handle it, as im still struggling pretty extreme with my mom's passing sometimes. I have the most vivid worst nightmares about her, and have started having them about him.

His all I have left in life, and when I think about him passing, I recall my childhood memories, and all the goodtimes.
Im so scared.