That's a good question. If the parents are always FIGHTING, and harsh words are said all the time, day in and day out, it may be best for the kids if you separate.
But if you two can be civil with each other, it might be best if you stayed together. The children are ALWAYS the ones who get hurt in a divorce or separation! ALWAYS. They somehow always think they're the reason for the split, no matter how many times you tell them it wasn't their fault.

Plus they kids don't dare show any preference towards one parent or another, even tho they might feel closer to one. They feel guilty if they want to spend more time with one parent than the other. They carry GUILT with them all them time! GUILT -- do you have any idea how horrible that is for a child to deal with? A child should NEVER have to deal with guilt! It hangs on until adulthood, and screws up their whole life.
There is so much you need to think about as far as the children go. They will be VERY effected with a separation/divorce. You need family counseling, if you're considering something like this, because the children should have some say in it -- and they need to understand what's going on. A good therapist could help them understand. See a therapist with everyone before you do anything, please! Hugs, Lee