Sure our thoughts can affect us I think that's what you're asking but I was confused with yours because your worst case scenario was "comforting" to me. I use that thought now to help me when things are bad. I think how we take what we think, one way or the other, is what gets us? There's no "law" we have to take it one way and not the other, nothing inbuilt I don't think.

My mother died when I was 3 and my aunt told me in my 20s that my father had said at that time, if he and my mother had known how sick she was (from before I was born) they wouldn't have had me. I took that to mean, not that they were sorry they had me but that they were glad they didn't know how sick she was! See? You can look at things either way at any time.

Your "goal" in thinking something would be more important I think; you said that with your prayer the constant family turmoil was weighing too heavily on you. I'd work to let go of that (now that you're an adult), to let people care for me rather than allowing myself to believe as a child it was my job to try to take care of others and situations beyond me. That 10 or 11 year old child should be given a well deserved "rest" and comfort that, in the rest of her life, it's not going to get that bad, you'll protect her from such family turmoil.