I am so sorry, Lisa. Everything you and your daughter did, you did out of love so don't ever regret that.
He chose his path and sadly this is where it led, nothing you or your daughter did or did not do could change that.
Forgive yourselves or maybe your life for not turning out differently, release your regrets and embrace the memories of better days, better times and take comfort in knowing that he knew how much he was loved.
May you both, one day soon, find peace in knowing he suffers no more and rests peacefully in the arms of God.
Hugs