I'm not even to go down the route of comparing down syndrome to stuttering. It's totally different. If you stutter so severly that you're considering killing yourself, why not just move? Go to another country where there is no expectation to be able to speak at all. Do something other than wallow. I get it sucks. I barely spoke for a number of years but learnt to hide it with confidence gained from moving abroad. I stutter a lot back home, I barely stutter in this new country. I appreciate that your mother feels sadness for your stutter, but I promise you she does not regret having you.