Update based on your added info: You've been back with him for about a year and it was 4 or 5 months ago that he started this again... that means, for the entirety of your 10-year relationship, he acted non-jealous and non-controlling for NO MORE than 8 months.... changed? Not likely.
Original: Sounds like the kids are growing into young adults, moving more into a friend relationship than a strictly mom-child relationship and in his mind they're just like the rest of the people he's driven out of your life - just someone else to divide your time between.
I get that you've been with him 10 years, but my advice would be to RUN as far and as fast as you can away from him and this relationship.
It's not healthy - separating you from friend, family, and work... NOT OKAY. NOT HEALTHY. NOT NORMAL.
And then to move onto your kids...
Here's the question - how much are you willing to give up with your kids to stay in this relationship? Because I guarantee that he views them the same way he views his own daughters - they're not in his life and he probably couldn't care less. What's he going to care if your kids aren't in his life or yours?
At some point he's going to push this to a point to where your kids will separate themselves from him and, ultimately, from you, to maintain their own mental health. What will you do then?