Any mistake we make that ends up in the death of our chickens is just so painful, there are no words to describe how it makes you feel. All you can do is hang onto the hope that it will hurt less each day you manage to get through.
Like, Blooie and the others, I feel your pain. It's sick-making. Nothing else comes close.
A little thing like tying a cotton or jute string to the heat lamp to secure it so it won't accidentally fall can be our undoing when the hot metal shade heats the string to combustion, falls down into the bedding underneath, and very quickly all is lost. The bulb itself doesn't even need to come into contact with a flammable material.
Other times, chickens themselves, in the midst of a squabble, can knock against the heat lamp and jar it out of position, resulting in one of the chickens catching fire and what then follows is pure tragedy.
There are just so many different ways heat lamps can cause more heartache than we can handle that the word simply must get around that they shouldn't be used around chickens, period.
I am so, so, achingly sorry you have to have this awful burden of grief.