D.A.
I'm sure that you have realized this, but just to remind you, there is a lot going on in your family from what you have said. The biggest thing with teens when they get to that "I know more than you phase" is to remain consistent with what you expect. You also have to stay firm and not give in, which I know can be easier said than done, especially when you have run out of fight. Last but not least, there have to be consequences if they don't comply with what you need from them. Don't give them that ride, don't babysit, or whatever they are needing/wanting above parenting. Allow them to see through the rewards your youngest son receives for being a respectful kid what they are missing out on.
I have been divorced for the last eight years and have an eighteen year old daughter who is pregnant, boys that are 15, 12, and 9. My 12 year old is the kid that reassures me through his behavior that I am doing it right. The other ones are behaving like some of the kids they have as friends and it is a constant battle to keep my home from deteriorating into the kind of atmosphere these other kids are living in. Unfortunately parenting is the hardest job in the world and it comes with no instruction manual.The best thing that was taught to me was to remain calm. I came from a loud environment as a child and the loudest person always seemed to get what they wanted (my parents). But if I can successfully deescalate what is going on by first of all quieting the atmosphere, the rest seems to go smoother. I start by keeping my voice calm and low. If they're loud they can't hear what I have to say and they have to quiet down to hear my input. It's not the easiest technique but it has been the most effective approach in my family. Also I would incorporate your first husband in whatever approach you are taking because you two have to be on the same page. If the kids know that regardless to what's going on the two of you are on the same page with what you expect from them it will be harder for them to run over you. For some reason, kids just respond better if they have more than one person telling them the same thing, especially if they think the people aren't on the same team.