Hi OP: firstly sorry to hear you are having such a shit time. i also had these concerns when I decided to leave a 21 year relationship. For a long time I felt as though it was better for us to stay together, but it was toxic (I recognise was emotionally abusive). I have two boys, and to think they would grow up seeing that as their benchmark of what a healthy relationship was was the deal breaker for me (and also understanding that I did indeed deserve to be happy).
Since I left, the kids don't hear us arguing, we are mainly able to be civil in front of the kids, and I do think in time we might be able to be firends. He is learning I won't put up with shit behaviour anymore but its taken nearly 18 months to get here. In two weeks its our youngests birthday and we are both contributing and will be there and it will be fine.
The kids spend every Thursday and Friday night with him and every other weekend. They get much better quality time with their father, and I get a break. It was hard at first, but now I enjoy my alone time. The boys tell me he is much calmer (when they used to also get shouted at all the time), they never complain about going there, they like to be with him.
Whilst they would both probably say they would prefer if we were together, and they don't "like" the situation both understand (they are now 10 and nearly 7) and tell me they are happy. My eldest has changed so much, he used to be very combative and stubborn, he now demonstrates empthay and emotional intelligence most adults don't. He is 100% calmer (he still has moments) and we talk a lot about how he feels. The youngest one has also shown his creative and cheeky side much more, before he would be frightened of being told off all the time I think of making a mess or upsetting his dad.
The biggest change in me is I am able to parent how I want not how he wanted me to, I am comfortable in my own home (I moved out), and I am happier than I have been in years. I still cry, I still have down days but on the whole my life is good. I was on edge all the time with how he might react, I changed my whole personality to suit him better.
I think the damage done to them by staying, would far far exceed the damage they may or may not have form our seperation.
It hasn't been easy, and your children are younger, but you cannot live in an enviroment like that without damaging yourself most of all. I honestly didn't know who I was anymore, still not 100% sure I do, but I am enjoying getting there.