have you considered the possibility your husbands gay?
one thing for certain is he is not ln love with you and has it in him to live with his "sister" for a long time. fun wow!
if you dont have it in you to live like this also, then GET OUT! the sooner the better. oh, and take the responsibility for breaking up the family, your children will be proud of you in the end, rather than living with this notion that marriage is suppose to suck.