How do I “read” a variable on a while loop

You can write:

while IFS= read -r line
do
    echo "$line"
done <<< "$the_list"

See §3.6.7 “Here Strings” in the Bash Reference Manual.

(I’ve also taken the liberty of adding some double-quotes, and adding -r and IFS= to read, to avoid too much mucking around with the contents of your variables.)