E., I totally empathize with you and your husband. It is sad for the children when one parent stands in the way of a full relationship with the other parent. Studies suggest that kids of divorce do best when they have consistent contact.
I'm currently in a similar situation. I think your husband will be more successful if you stop having expectations of other people, and rely upon yourselves as much as possible. Here are some things you can do that have worked for us:
1) Volunteer occasionally in the classroom and get to know the teachers. When the teacher knows you as individuals, she will be more likely to keep you in the loop.
2) Talk to the school principal about your problem and enlist his/her help. Often, taking the problem to the next level makes everyone more aware of it, and more conscientious about keeping you in the loop.
3) Offer to stop up at the school once a week to pick up copies of the hand-outs. It may be easier for the teacher to put copies aside in her room for you, than to remember to get them in the mail.
4) Our school has a web site, and voice mail. It's hard for the teachers to ignore you when you're using the email and voice mail to remind them constantly.
5) Finally, if your husband and his ex- would consider mediation, sometimes a good mediator can both help you solve problems like these, and work to bring down the level of animosity - beneficial for the kids too!
Good luck!
S.