(You will not get a satisfactory answer from why the kids get dragged in. They just do.)
Then you are not protecting your children....and you are not putting your children's welfare above your own and in doing that you are being selfish. If YOU are not able to stop yourself long enough to turn to your children and calmly say "please leave the room", "please go outside and play for awhile", "please go to your rooms for a bit while we discuss what we need to"...whatever, just get them out of the fray....YOU aren't protecting your children. I find that truly sad. You CAN conciously stop yourself in the heat of an argument and say "STOP"...but you don't. I won't even get into the why's of it.
Regardless of what your W does/doesn't do in these arguments...how she drags the kids in, baits them with questions...whatever (which is equally as wrong because she doesn't shield them either). YOU still have the power to protect your children, yet you CHOOSE not to. I feel for the kids. Kids absolutely should not have to endure this.