Dear merry0011,
Congratulations on going back to school in December. But I do not understand how you can leave in middle of semester to go to Dubai.
You husband tells a sad story, but be careful to store that away so that you do not swallow that all the way right now. It could be true.
If your husband had a change of heart, then maybe he makes a new start. I am skeptical of stories of husbands who are with someone for 10 years and father 4 children then are gone. It could be true she dumped him, but he could have just as easily been the one that dumped her. I am not sure, but I think a certain amount of skepticism could be helpful until you know him better.
Be careful that he does not insist on having children right away. In USA they use birth control but that may not be an option for you. Having children will make you responsible for their raising. If he has no money how can he support you and your children if you have them? Does he have a job?
I wish you the happiness, but be careful he is sincere and you have a heart felt relationship.
I would say rather than make him forget his bad past, find a way to make a happy future for yourself with room for him to participate in it as an active provider for his wife and children if that is in your future. Try to finish school before children or education is much harder to complete.