I don't think your son will be taken away if you tell the truth about what happened, the fact that he was poised to hit you. Also your son won't want to leave his home. Please don't worry about that but, goes without saying, don't slap him again. You know it was wrong and don't be afraid to say you're sorry.
What is more difficult is living with your boy's behaviour now you are, presumably, confined together most of the time.
I can't offer advice, am not qualified to do so and have no similar experience as a parent. However, attempting to put myself in your position, I think I would try treating him as a grown up, asking for his opinion on things and making suggestions. He knows he's being pain but may respond to reasonable, adult talk.
If you have a room, other than his his bedroom, that he could use to do his own thing, that would be good for him. His own little den. Or if you can't do that, maybe his bedroom is big enough to be a bedsitter. Somewhere for him to be private. The biggest advantage would be not falling over each other all the time. It could be quite an exciting project for him too.
Tell him you want him to join you and your partner for meals or at least one meal a day, for him to clean up after being in the bathroom and to sort his laundry but other than that, he's free.
It's worth a try.
Reading back what I just wrote I can't help really wishing my parents had given me space, privacy and freedom within our home. I had none! That's probably why I appreciate it so much now.
Like you, I have one child, a son. He's forty and an international musician (at the moment not going anywhere of course, all dates and tours cancelled until further notice but he is doing some quite interesting and exciting work from his home); he had loads of freedom and no hassle from us - plenty from school at times but we weathered that and now, of course, his old school is immensely proud of him (typical).
This is not a boast, I'm just telling you to illustrate that it works to tailor your parenting to suit your child, who is an individual. I've been on both sides and can assure you, I was a horror! When I look back I think it is a miracle that I lived beyond my teens.
All the very best to you, you have my sympathy and please keep coming back here to tell us how things go. I'm sure others will be along with better suggestions.
Take care.
