I use Textra on Android and I can select which parts of a message to copy. I’m using the paid version and have for years, so I’m not sure whether that’s a standard feature or premium. The day Messages stopped letting me color-code each conversation was the day I quit using it; I can’t tell you how many times each person being a distinct color has saved my ass from texting the wrong stuff to the wrong person.
Oh man, I can’t even imagine the devastation you felt. I am so sorry that happened, and I’m grateful that you can talk about it now.