Well instead of just upping and leaving you could give him a warning first?
What he's doing is unacceptable and it's not good for your children to grow up thinking it's normal or okay to speak to your partner that way.
I was with someone for a very long time also who I literally thought I could not live without, which is why I never left, even though it was painfully obvious I should have.
I really did believe that I would not be able to cope with this person, yet once I left the weight lifted and I could not believe I ever thought that way, for almost a decade!
Tell him you need to talk and then sit him down and tell him how the comments made you feel, why they are not acceptable, why they will eventually harm the children as well and have a negative impact on their own relationships.
Lay that out for him and tell him if he does not stop then you will be leaving.
Once you have his reaction tell him you will now go away and think about it. Come back here and tell us the reaction. Don't react. He could react violently, with threats, or abuse, threats around the children etc. etc. and I think you could do with some advice at that point from people outside of the situation.
If you do it this way you will achieve the following:
You won't have just upped and left on a whim and no can say you just ran away over nothing.
You will learn a lot more about him from his reaction and know where you stand a lot more than if you just left.
You will know that you gave this a chance and were very reasonable.