I don't condone his actions for one minute, he's at that point in his life where he wants more but doesn't actually know what he wants.
That said, 2 lovely children and a devoted wife sounds like he has it made.
Ideally you need to look at the fact he's left and move on with your life. This is SO difficult because it's obvious you adore this man. However all he sees is his wife crying and pleading for him to come home whilst he plays the big man with all your feelings....
Want to get him back? Get your life back first and he will follow.
If you go 'OK, you've left' and quote the words from the amazing Beautiful South song 'the freedom that you wanted back is yours for good, I hope you're glad' and crack on with your life...he'll sit up and notice that actually you aren't dependant on 'just him' and this will crush his male ego.
I know we are in lockdown so do this on your restrictions but do you have a close friend or family member? If so, meet up...have wine, cry on their shoulder.
Go for long walks or crack on with your hobby....ignore his messages for a while as you are busy.
Present yourself differently...after lockdown maybe change your hair, lose weight, gain weight, put make up on...do whatever to look your best or if you want him back then gain his attention....personally do it for yourself cos if you look great then you will feel great...
You will also learn that actually you have an amazing life with or without him...do stuff with your kids if you can....
If you learn to love yourself you will realise how much you need to protect your feelings and the fact he's done what he has is poor form and you deserve better.
Good Luck and I hope you can work things out.