Can you still be friends?

Nor can I offer you any reassurance.
If your spouse has behaved so poorly that you have had cause to get away from them, they are most unlikely to have a personality change.

But, for what it's worth, here's my experience.
I left in October 2009, and as you might imagine, the conversation that led up to this were quite lively, and the mood in the house was unpleasant to say the least.
And, in the immediate aftermath, my missus wasn't beyond making abusive phone calls or sending inflammatory text messages.
However, she would find herself with dial tone only if such phone calls became abusive, and no responses to the texts.

Over a month or two, she twigged that her tactics were going nowhere.
Then a mutual friend died, and I rang her up and suggested that as I was going to the funeral, we might as well go together. We did. Had some reasonable exchanges during this outing, and things began to thaw.
To the extent when I travelled to the city to see the kids, I'd stay at the old marital home

Gradually a new relationship developed, based on the facts. That we had been married for years, and had two kids, but that was 'then' not now.
I had also demonstrated good faith in our financial split up and had conducted myself with a reasonable degree of decorum through the whole process.

Oftentimes when I visited, we'd go out for a few beers and a feed, talk about old shit and generally behave like adults.

In April 2015 she took ill and died suddenly.
Thank fuck we had made the peace before this rather permanent end to our deal.
In fact I think that our relationship, post marriage, was probably "healthier" and more truth based, than it had ever been.

I would suggest this.
If you are thinking you can have a trouble free parting you are probably kidding yourself.
But, if you conduct yourself with dignity, with fairness and goodwill, then if your former spouse has any class about them at all, you will be able to thrash out a workable relationship.
But it is very likely to get pretty lively before then.

So yeah, it is possible to remain friends, once the heat has died down.
But the facts are that you control only your end of such a situation. If your former spouse chooses to remain a jerk, there is fuck all you can do about that.

My ex and I are friends. Not great friends but friends.
He called me yesterday to talk about if I saw the football games Sunday, then of course we spoke about the kids some too. Last week he called me and I had to hold back breaking into tears and crying on the phone. I do still love him. I can't say that I'm in love with him because of the years of rejection and I don't really feel sexually attracted to him. I think if the kids were not in the picture there probably wouldn't be any contact. It's a very sad story.
I am an example of what you describe though.

That is exactly right. I had already grieved the marriage but he didn't.
The night I moved out, middle of the night - he was screaming at me and he was so angry but I stayed calm, I didn't yell back, I just loaded my car lifting heavy boxes while he watched and yelled and I drove away. A week later he calmed down. I basically kept telling myself he's angry because he's sad I'm leaving and I know it's true. I still deal with bouts of sadness when I think about what should have been because we really could have been great.

My wife and I have been separated for approximately three years, and are working on the divorce now. We're cordial, good co-parents, attend birthdays and other kids activities together, and generally conduct 'business' fine. She's business as usual and doesn't seem emotionally affected by the change in our relationship. That's consistent with her indifference during the SM, I guess.

I can't imagine wishing and hoping we'll be friends. I die inside every time we interact, sometimes cry, avoid eye contact, avoid looking at her body. It's all too painful a reminder of a torturous 15 years. I hoped and tried so hard for so long, and still it didn't work. I wish it could be completely out-of-sight out-of-mind now, but it will never be, because we have four wonderful kids.

I can only speak for myself and reiterate what others have said about you only being able to control your half of the post marriage relationship. My X and I are remain good friends. Her well being and happiness is still important to me. We attend the same church and often see each other at get togethers with shared friends. When she has a maintenance problem with her house or auto she calls me. We date some and often spend an afternoon together in the summer riding my Harley to a wine tasting or some other activity. We kiss and are intimate,(I'm always hard at work getting her titties out into the light) and on rare occasions still have sex. So it is possible to come away from a very unhappy set of circumstances with a spouse and both of you find yourselves together in a better place.
Like bbgirl I grieved for a marriage that should have been great for both us but wasn't.
No one cannot assure you the post marriage will be smooth sailing, and personally I could not have continued to live with my X. It was simply too stressful for both of us. Me always wanting to pump my little swimmers in her and almost always being refused and for her having to deal with a spouse that she felt constantly wanted physical and emotional attention.

Well said.  I think that most (if not all) of us grieve for something that should have been but wasn't.  I'm still in it, but am no longer depressed about it.  Just sad / disappointed at where it has led.