Lucylu19, first off, welcome. I'm so sorry that you had the need to find this site, but I'm glad that you did, so we can offer you support.
The 180 is intended for your benefit, to make it able for you to detatch a bit, so you can work on what your needs are. It doesn't mean that you do everything in the house. It means that you mentally detatch from your WP and take the time to work on you.
So, you need to stop being a single mom to those children. They are HIS children too and he needs to step up to the plate to help take care of them. Note I did not say help you take care of them or assist you in taking care of them. I said HE needs to take care of them. This is where he learns what it looks like, to be a single dad with visitation.
Your talk is of finances and children only. This falls under the guidelines. Draw up a child care schedule. You get them x-amount of days from this time to that time. He gets them x-amount of days from this time to that time. If you're living together, you leave when he has the children. You are NOT there to help him he is in charge because thats what a single dad does when its the days when he has custody of the children. You dont' cook for him, clean for him, shop for him, nada because, well, single men have to do that for themselves. Some allowances may be needed for the newborn especially if he is breast feeding, but no allowances need be made for the older children.
You are no longer his soft place to fall. Use one of those days off to go see a solicitor and find out what your legal rights are because you very well may need to file for child support and some sort of maintenance. Knowledge is power go get some.
And keep coming back often for support. (((hugs)))