Laurie, I am so sorry for your loss. My Arabian gelding was on psyllium for sand and he also colicked and we had to put him down. It is now my opinion that psyllium actually causes colic and I won't use it. But this is proof that sad stuff can happen no matter how much you love and care for your horses, I am sorry!
Oh Laurie I'm so very sorry that you have lost your special girl. My heartfelt sympathies, it is never easy to lose any of them, but with the ones that strike that special chord it can leave you feeling as if your world has fallen apart.
It was not sand (though I had treated her for that just in case)- the hospital truly now thinks she had an entrolith or something else going on in there that would have required surgery but it was too late.