Okay, couples have recovered from this and even worse, however it depends on a number of things.
I feel it's risky to take him back and you should look at protecting you and the DC financially if you do so.
Consider the following too:
He left you and 4 children for an online relationship.
He moved so far away and didn't care about not seeing his DC regularly.
You have a man who doesn't 'have your back' and isn't a safe partner to trust with your heart.
Can you trust that this won't happen again, if you don't know what caused it?
What has he done besides begging to let you know he's serious and remorseful?
Did the DC know he left for an OW?
How will they feel about a reconciliation?
How will your family feel? Will they accept him after this?
If you do take him back, with no consequences, stipulations and conditions, you send the message that this is not a deal breaker for you.
The heart is a precious thing.... Don't let him break yours again.