You’re wanting too much too soon op.
If he hasn’t met someone else you probably wouldn’t be that bothered that he’s left. But finding out he’s been cheating with another woman and involving your children is a huge betrayal of trust not to mention it’s going to be a massive dent to your confidence and ego (which is already on the floor)
You say “how could he do this to me, I trusted him?” But c’mon op - you know he’s a lying, faithless pos - you’ve detailed his terrible behaviour here on this thread. This man has shown you completely who he is (a selfish, nasty, abusive bastard) for a while now and you’ve chosen to ignore his behaviour for the sake of staying with what you know and fear of the unknown.
The only thing that will help you get over this is time and possibly some therapy to work on your low self esteem. Just think about all the crap you’re not going to have to put up with from this man now - he’s the ow cross to bear now!
You and your dcs will end up so much happier without this toxic influence around but it’s going to take you time and self reflection to get over it. And pining over him and trying to convince yourself he was someone you need isn’t going to help you. Be kind to yourself for now - make sure you’re eating and drinking enough and just do whatever you need to do one day at a time. You are very hurt and confused and it’s going to take a while before you realise you really are better off without him.
I had a horrible breakup earlier in the year with a toxic man whom I’d only been seeing for 3 months and it’s taken me a really long time to get over it. I feel a lot better now but I still have moments of ruminating about it and feeling upset. I can recognise the reasons why it’s been so hard for me to get over though - I thought I was madly in love with him and he with me and then it turned out he was married. He basically ghosted me and then told his DW a lot of lies about what actually happened. He told me a lot of really big, shocking lies about his life that turned out to be bollocks. I feel that I was taken in by a charlatan and my trust was abused which massively fucked with my head and I felt like a suffered ptsd from his behaviour. I was so shocked and hurt and at first I wanted revenge and had very dark thoughts running through my head. But eventually I realised that would achieve nothing but making him think I was obsessed with him, so instead I comfort myself with the knowledge that someone that screwed up is never going to be happy inside and content with his life if he’s willing to go to such lengths to cheat, lie and lead a double life.
Im secure in the knowledge that I’m a good person who doesn’t lie and has the capacity love and treat people kindly and with respect. You are too op - it’s good that you don’t understand his behaviour bc YOU are decent and a good parent who behaves in a proper manner so what he’s done is incomprehensible to you.
He on the other hand is trash.