How about, "well I appreciate your opinion, but I don't recall asking for it, so if you don't mind, I'll just forget this conversation" A**hole!
I'm sorry your dealing with morons on top of having to be the best Mom you can be to hurting kids. But the morons are easier to dismiss - please do your best to accomplish this for your own sake.
I can't imagine how badly you and your kids are hurting. The acting out doesn't surprise me one bit. I wish I had a failsafe answer on how to fix it, but I don't. They talk to you, maybe not alot, but at least some which is good. They know you're Mom and they also probably know that their behavior is hurting you; they just don't know what to do to stop it.
I remember when my daughter started driving, I heard about the "new driver contract" and found it online. I used the basic contract and modified it a bit with my own rules. The gist of it was that there were certain things she absolutely had to do to maintain the car and most importantly, keep herself and her passengers safe. There were rules that could NOT be broken and maybe others that we could talk about. As she got more experienced as a driver, things were modified (like how far away from home she was allowed to drive) It wasn't perfect, nothing is, but it did give us a starting point and she knew the boundaries she needed to maintain if she wanted to stay mobile.
Do you think one or all of the kids would respond to "making a deal" with you about some of the behaviors that are more difficult and harmful to them and all of you as a family? For instance, if they get a parking ticket, they pay it and lose the car for a week, except for work and school. If they get a speeding ticket, again, they pay it, but they lose the car for longer and they have to reimburse you for the lawyer, if there is one. By the same token, if their driving record is perfect for a year, you'll make an insurance payment as a reward.
I'm sure there is alot more you're dealing with other than car trouble, I'm just using it as an example.
If you fall down 10 times, Stand up 11.