Re: Husband is "willing to share me"!!
This is totally wrong of him. Don't let him disrespect you like this. Tell him you want a separation till he gets his head on straight. Maybe it will shock him into realizing what he could be giving up if you leaven him permanently.
Don't be snowed by promises. Insist on some time apart - and then if you think it is worth it, counseling. There is no way you should subject yourself, and your kids to something like this. What does he think marriage means anyway?
You might find doing the right thing frightening, but it's worse to be pressured into doing something you believe is inherently wrong and starting down that path.
Take courage girl, get the support of your family and stick to your guns!