"He's never been diagnosed with anything"
"Family don't want to help because they think I created all this by not being firm enough "
"I'll admit sometimes I give Ds the money that's for Dd's activities,revision books ,school equipment just so he doesn't kick off."
There could well be more to all this, but this looks to me like a situation where your son has abominable behaviour and rather than setting boundaries, you are effectively paying him to be a shit.
Sometimes you have to do what you have to do. But...I find it odd that you would consider renting a house good enough for a modest party, while accepting that your own house is trashed and not suitable for visitors. If it isn't suitable for visitors, it isn't suitable for you and your dd. this is the thing. You have a son with terrible behaviour and no diagnosis and either you have to massively step up your parenting or you have to work out what extra help he needs, and get it.
Weaselling out to an airbnb isn't the answer.
I know that might sound mean - I am sure it is - and of course it goes without saying that there is a lot I don't know.
But bringing up children properly is hard. It is being strong and consistent when you have nothing left, every single day. Some people (perhaps temporarily) don't succeed in doing this. And when that happens their children are not well brought up. It happens. Not every case of an unmanageable child is a case of SN. Sometimes it's a badly behaved child.
You have an absolute responsibility to fix your home life for your daughter. Friends are important, yes, but home and family are her bedrock and you have failed her.