If you suspect his wife has a hand in this and sees your emails (not sure how she could alter them but I am not a pc buff) why not have it changed to a standing order or direct debit not sure what you call them. That way it would come straight out of your x husbands bank straight to yours on a given day each month that way you are free of the worry as to whether or not it turns up. Then you have no need of the possibiity of her having anything to do with you and your x's arrangements.
I thought this kind of arangement was the norm in a Divorce case. I take it that it was court ordered. Sorry about the job, hope you hear soon, have you anything else in the pipeline. Try and habe a good Easter,are your parents coming? Take care.