It "should" be:
Honestly ðis þread makes me sad. Can't a fella be a li'l quirky in peace?
You can make the þ sound by itself without using your voice. It just sounds like air coming out of a tire. You can't make the ð sound without also making a vowel sound.
Ðough historically the þorn was often used for boþ as well, and it's definitely tricky for modern Eŋlish speakers to distiŋuish.