Please talk to a lawyer before you move out of the house. If a parent leaves the family residence, it is sometimes used against them in court to show they abandoned the family. This could hurt you in your custody negotiations. It sounds like your H is being civil right now. Use this time to find a lawyer and get your ducks in a row before making any drastic moves that could influence your divorce settlement. This is especially important since you say you do not make as much money as your H. Is there another bedroom in the house you can move into? At least then you won't have to share a room with him. If you feel you or your kids are in danger, then of course what I wrote isn't good advice. In that case, you need to get out of their immediately.

Try your best to have an amicable divorce, get your H on your side in putting the kids first, and he can set the tone with his family about what is off limits for them to say to your kids. It's not impossible to do this. It's worth a try, don't you think? Kids first. Kids first. Kids first. Try to get him to see that. If that's not possible, so be it, but at least you gave it a try.

With your H's assistance, they need not blame either of you. Try to get your stories straight with your H so that both of you tell them the marriage was no longer working, etc., so that is why you split up. Avoid placing blame on either parent.

No, you don't have to prove anything to the families. But I do think you should give your H an explanation on why you want out of the marriage. It can be brief. No, you just can't go, because you have kids.

Here is a book I highly recommend. Get a copy for you and one for your H.
Mom's House, Dad's House: Making Two Homes for your Child

Another link in case you're interested:
International Academy of Collaborative Professionals

Best of luck. Feel free to PM me. I am at the tail end of a divorce. It can be done!