Well, I can't say I am surprised. Kinda saw the bus coming!
But, over time, the kids will see through him. He isn't changing any time soon, and they will see who he is as they get older. Meanwhile, you will show them a great example of a responsible, loving, kind, faithful, and generous adult. As will as a bunch of other good words that escape me just now! And, more than likely, one of these days you will be in a new relationship that will show the kids a better example than Dan did.
So, be mad, 'cause he deserves it! But be glad... it's done, and now you can really move yourself forward!