He's not a part of your family and he knows it. He knows he chose the other situation, and he's making you the bad guy by complaining, essentially, that you are not a good parent to him because you don't do everything he wants. He's also justifying his decision to live elsewhere by making it clear that the little kids have all the choices made in their favor (in his mind). ("See, my mom loves her new family more than she loves me.") Some of what he's doing is also testing - how rude and miserable can he be and still have you love him?
It's also likely that he is not being raised with any manners. He's also a teen and they do whiny stuff a lot, and they are hard to please. It's hard enough when they live under your roof and you have some leverage, but in your case that's not the situation.
I don't know how much you see him, and whether you pay child support. If you have shared custody, then there's probably no CS. So he may be thinking (or possibly have been told?), "Your mother doesn't pay anything to support you, so she can at least give you a good vacation and pay for your friend."
I wouldn't take him on this sort of vacation because he clearly doesn't enjoy it. I don't think you have to rub it in his face that you're going away and he's not - just go. If he asks, I think you can say it wasn't his sort of trip since he was so miserable last year. However, you have to be gentle about planning something you know he won't like and doing it anyway.
I would try to work with him to find some things he DOES want to do with you, and then try to do just some mom/son activities. Leave the little kids at home with their father and do something with just you and your son. Or leave the little ones with Grandma or someone else, and just do a few adult activities. He's not going to want you to go to a rock concert with him, but maybe a beach day or a science museum, whatever his interests are, and a nice dinner out. If he's miserable and rude, you can ask, "Would you rather not be here? Would you rather go back?" And then take him back. But try it again in another month or two. Don't give up. And DO make these outings your treat at least in the beginning, because part of him still feels like a kid and thinks the parent should be paying. I wouldn't accept a lot of disrespect, believe me, but I'd just end the outing sooner and try not to fight endlessly about it. Maybe if he participates in the planning, he'll be more positive. But if he's rude, you can say "Gee, I thought you would like this since you chose it. We won't do it again but maybe we can find something else."
He could be scared about being 18 and what that means - a lot of kids don't feel prepared for jobs and college and so on. So it's possible he regresses a bit. But still, it would really be nice to have a conversation with him about what he's doing, what he enjoys, without having little kids to deal with.
Try to stay in his life, but don't be a pushover either. He can't learn that it's okay to treat people that way, and it's not okay to treat women that way.