Formerly single mum of two boys - new partner unexpectedly moves in. Please help!

[MC687]

Ok. So I'm a newbie to posting and I'm really hoping that you guys will be able to lend a friendly ear and offer some constructive advice!
I was a single mum of two for over 12 years and a few years ago began a relationship with my current partner. Things were going well for all of us, my DC thought he was cool and the two of us were getting on brilliantly - up until 2 weeks ago!!! Just to give a bit of background, he is a competitive BB (I also compete). His dad is an alcoholic and his mum after having him suffered severe PND and was the diagnosed with bipolar and a form of schizophrenia. He's also 13 years younger than me (not that that should make Any difference!); a fortnight ago he competed in the national finals and I made the suggestion that post comp, he comes and spends some time with us the week after, following the show. Unfortunately a few days prior to his show, his alcoholic father made an allegation against him (he has done many times in his drunken states) and so my DP had to go and be processed ant he station. Upon advice from them, he came to stay but what was once a suggestion to come and chill out has now escalated into something way more!!! We'd talked about eventually living together but I hadn't quite anticipated for it to be put on me/us so quickly!!! Needless to say, the pressure is now being felt!
My youngest, has now done a 180° and says he hates him (previously, he thought he was nice and kept asking "when are coming to stay here?"), he's angry, hostile and very belligerent (a little bit of puberty in the mix there as well just to mix it up !) And he and I keep squabbling/bickering. I feel more like his mother than I do his lover/partner! Instead of having just two children it feels like I have three!!
I'm now extremely worn out and am feeling like I'm trying to keep Everyone happy but in the process, am not feeling harmonious about anything!
Can anybody give me some pointers please?!?

It's not a hobby, he's professional.

He can afford his own place, definitely. Perhaps I was a little unfair calling you bitter carlson, so apologies.

'Hi BB BF. I have had a chat with the kids and this isn't working for any of us. So this little holiday needs to end. Today. Shall I help get your stuff into your car/a taxi? Cheers'.

I'd go with, "It's been great having you here, even though neither of us would have moved this fast in ideal circumstances, and I'm glad we were able to help out whilst you found something more permanent..."

and then cowardly let that silence hang there for him to fill

Perhaps a conversation along the following lines could take place.

"When I suggested you come and stay for a bit after the comp I meant for a few days.

We talked about maybe moving in together but what I had in mind was when the kids had ceased to be dependent and had possibly left home.

This situation about your father is unfortunate but moving in with us permanently was not what I had in mind.

The prospect of you joining our family has unsettled the dynamics with my kids and if it was going to be permanent I should have had the opportunity to discuss with them/warn them beforehand. I suspect they are now being faced with a fait accomplit and that's not fair to them.

The situation as it stands now isn't working for any of us so I think you need to make plans to live independently of us for the time being."