He's left and I'm not coping

[Bones2017]

My husband left me and my kids (7&3) 10 weeks ago. We've been together for 20 years since we were 18 yrs old and married for 5. It seemed out of the blue to me at the time but looking back now, things have been harder for a short while.
Since last summer he seemed distant. He'd sit in another room on his computer whilst I watched telly. He'd be late home from work most nights. I found porn on his computer. He was protective over his phone also. One morning he was getting a text from a woman and he explained it was a colleague letting him know she'd be late in. Maybe. There was impotence issues also which I put down to him starting to smoke again. I had asked a few times if we were ok and if he'd met someone but he always denied it and reassured me that he loved me.
There was times when I didn't know where his wages were going and I had to work extra to make ends meet. He took out Payday loans behind my back also.
So the night before he left, we had sex and it was different. He really pulled at my hair and he hurt me. When I fell asleep, he went through my phone and read some messages to friends that I'd written about some of my troubles with him. He then sat me down the next night and told me that there was no trust anymore. He said he needed some time out and would be leaving me. Of course I begged him to stay and thought it was all my fault. He was very angry with me.
2 weeks after leaving me, he was viewing places to rent. He wants me to stay in the house. Wants me to carry on as normal living the life we've built together whilst he has some space.
He's denied anyone else being involved twice since he left and has said he felt like he was in a rut. Poor excuse if you ask me. I feel lost. Don't know how to carry on in the house without him. Unsure about my future and how this is affecting my kids. My confidence and self worth is shattered.
But what's killing me is that I really don't feel like I have a valid reason for him leaving. He won't go to counselling. At least If I thought there was another woman, id have closure. But no. And I'm just so broken and lost.