I never got a confession and I certainly never got closure.
I won't bore you with all of the details, but my exwh, out of the blue, gave me the "love you but not in love with you speech". He could have knocked me over with a feather at that point. We had just bought our new "dream" house about six months before that and our youngest was only 2 years old. I tried everything I could think of to get him to talk to me, and to act like the guy that I had married. But, it was like living with an alien.
There were rumors about him and another woman. I asked to his face at least 1,000 times if there was someone else, if he was having an affair, if he loved someone else, if he was thinking he might be gay - anything. I wanted some sort of answer besides, I just don't love you anymore. That made no sense to me. He denied it all.
I knew in my heart that there was someone else, but I couldn't bring myself to snoop. I knew that whatever was out there waiting for me to see, I could never un-see it. I wasn't strong enough for that.
He moved out a few months later, still under the guise of falling out of love with me. Oddly enough, he also sat on the fence for a few months even after moving out. I told him I would file for divorce because it seemed like he just couldn't pull the trigger and he told me no. He even made an MC appointment.
Sadly, the night before the first scheduled appointment, my best friend called me to tell me that he was spotted out with the very person who he was rumored to be with. That was it. I called him the next day and he still never admitted anything except that they had "just started seeing each other".
That was what I got. After 15 years of marriage and 2 little kids, I thought I deserved so much more. Even if we were going to get divorced, I thought I at least deserved one honest conversation and an apology. I got nothing. I was forced to end my marriage without really knowing the details of why.
It's taken me a very long time to process that and to acknowledge that I'll never get what I once desperately wanted. It's been over 3 years and lots of IC and I finally see that he's just too weak and too afraid and too narcissistic to let down all of those masks and to acknowledge what he did to me and our family. I'm his emotional mirror and he hates when I hold it up. He runs from me even though we don't fight, our divorce was pretty amicable compared to others, he sees the kids regularly, pays CS, and he even lives with OW now. I don't push back on a whole lot because, as long as my children are not being hurt or abused, I have no leg to stand on. He left; we're divorced. The reason he left or whether he really wanted to go or wanted to stay but was afraid of getting caught - those issues don't matter much any more.
What matters is that you find closure within yourself. You have to see him for what he is and see that people who can cheat, lie, and avoid are usually people who can't/won't stand up and fight. They are usually people who are much better at running away.
I know that somewhere inside my ex's soul, he realizes what he did and he realizes that he broke my heart and our kids' hearts into a thousand pieces. There is a part of him who gets that. There is also a big part of him who never wants to think about it again. He is more comfortable avoiding the hurt and, in the beginning, he was more comfortable being very cold to me so that he could keep his mind in that place. A while ago, during one of our rare phone conversations, I said to him that I know he avoids me because he's afraid if he talks to me or sees me he will actually have to remember me. His answer was "I know. I do that."
Your ex is acting heartless because it's easier than to come clean. You can't force him and, while your brain will come to understand it one day, your heart never will. It's non-sense and it's impossible to make sense out of non-sense. I think it's a special brand of hurt when you are dealing with a non-remorseful wayward who runs away. It's a true abandonment that leaves us with no chance to fight. I always say it's as if my mother or my father turned on me. I never thought my husband would turn on me like that and, I suppose that a part of me figured if he did, he would at least want to fight for me.
I'm sorry that you have to experience this pain too. I would suggest finding a good IC to help you process and to not rely on him to give you what you need. That will eventually only come from you.