Send your kids to Grandmas and tell your husband that you're doing it because you need time for yourself and to de-stress. Come up with a clear plan and timeline as to when, how and for how long the eldest of your children, at least, will be at the Grandparents.
Then, see if your husband can give his daughter a list of chores to do around the house -- that also involve helping you with the babies. I know she'll rebel but I think two things will eventually happen: 1) she'll start liking her Mom's new guy or 2) she'll start feeling like part of this family.
