Just my opinion, sweetie. Take it or leave it.
No good will come of discussing these issues with your H or you MIL. You've tried that a couple million times, right? I think that you still believe that they will listen to you, change their behavior and make things better for you. It's doubtful that they will do any of those things.
Unfortunately (or fortunately) the only one who can make you feel better is you. Accept the fact that their behavior may never change and take control of what you can control. How does it hurt you if Bree eats at a bus stop? I know you want to make sure your children have wonderful lives but really, how does it hurt you personally?
You don't have to abandon your children but, if you take a break from trying to protect and fix everyone around you, you'll be able to see more clearly what you can do to protect and fix yourself.
Hugs - L