I have not been through this and I cannot tell you it will get better... But my experience of life is that hurt and pain do lesson with time.
He's been incredibly selfish and I expect you are grieving the loss of the man you loved. But your ex is no longer that man. He has made his choices, all be it ridiculous and foolish to you (and probably every one else).
I also think New Year is a hard time to do things. It's so easy to feel down and daunted rather than positive.
I hope you will find a way forward that puts you at the centre. You have to work and parent your kids, they still need you so much; but please make time for yourself.
Find new things. Little things that will bring you joy.
He is not going to provide the hugs and kisses (and maybe dating now is not the right time), so what would make life easier?
Maybe things to look forward to, a weekend away with the kids or friends, maybe an art class, maybe changing something in your home or life, taking up something new, putting down something burdensome, or going for a promotion? Whatever it is, I hope you find it. XX 
Sorry not to be more help!