What a loser he must be... he just used you
I feel sorry for your children and can understand how you feel being let dumped by the one you love.
Sometimes it is easier to move on with no explaination as to 'why' Sometimes 'half reasons' are worse than knowing small bits that he confesses to you.
He either just used you as someone to visit and have a nice holiday or just to make 'him' feel better about himself.
It is hard for you to think straight right now... but, you must listen to your head not your heart. There is no future with him, that is clear. You have done nothing wrong, stop beating yourself up and dont be his dog, as this is my impression of what he thinks about you.
Be strong, you are worth more