My relatives weren't/aren't murderers.
I feel for you Sister...
When I think about loved ones who may be in Hell, it helps me not to think of them as Murderers. All they did, that I know of, was to break the First Commandment; they didn't break the Sixth one. My grandfather fought in WWII; he was from the greatest generation. When my daddy left us, he took my Mother and the rest of us in. The list continues: but he was an Atheist until the end; breaking the First Commandment...
I reject Double Predestination; God doesn't use it. You should reject it, since it troubles you. There's an alternative; Single Predestination. First, God is not far from anyone; we can reach for him. Second, Jesus said he would Save the Trodden Soil if these people Believed in him. A thing is established by two or three Witnesses. This overthrows Double Predestination; he gave All an Option to be Saved...
This reminds me of a time because of a stricter Calvinism I had, when I thought babies dying before they could Believe the Gospel went to Hell. I always thought to myself, if there were just half a Verse to change my Mind; I would. Who wants to believe a hard Doctrine if they didn't have to? One day I was listening to Woodrow Kroll, and he said he was going to show the Verse which said babies don't go to Hell. I got my pen out; I was ready to fight. He looked and looked, then said he couldn't find it. This broke down my stronghold, and I was able to really listen to him give me that half Verse I needed...
Can Single Predestination be good enough for you? Perhaps not believing in Predestination at all would be good for you; but it seems that you Believe in it. It seems you're having trouble, in part, since Double Predestination seems true to you. My suggestion is, accept Single Predestination; the Bible says we get to make up our Minds about these things. Some Keep one Day; some Keep another. Some believe Double Predestination; some don't...
Though we defend Doctrines above all here; sometimes we need to cry with you instead. God bless you and yours...