Dear Loving Wife and Mother,
Get Professional Help
I'm sympathetic to your situation and will gladly offer what advice I can, but this has obviously been going on for very long, and the best advice I can give you is to seek professional counseling, both individually and as a family. It's hard to teach your children any more when they're in their 30s, but someone with professional training and expertise can guide them (and you and your husband, perhaps) through a process of putting things in perspective and trying to mend faulty expectations or ways of thinking.
You imply that there may even be an issue with your husband's mental health, something that definitely calls for professional involvement.
It doesn't even matter what the specifics are of your husband's consuming passion. It's unhealthy when one person's dreams or desires overpower the needs of his family as a group and as individuals.
If you've read my replies to other questions at Love & Learn, you'll know that communication is a frequent refrain in my advice. It has to be open, honest, and be undertaken early and frequently for any relationship to be successful, and sometimes you need outside help to get the communication going. I hope that this course of action will help you and your family reach a positive resolution to this difficult circumstance.