It's a real shame when family members can't bury the hatchet but I know what you mean. I have 3 siblings and one of them, we play nice when we are around one another but it is a ticking time bomb and we both know it. I wish it wasn't that way but it's just something we can't get past. It's a shame and I don't really think there is a solution either.
It is good of you to pitch in to help even though as you say they "irritate the fool outta you." Which is an expression I have never heard before but am certain to use now.
Thanks for the compliments you civilized redneck @beelzebubba