I popped out this evening, and when I came home DH told me DS1 and 2 had had a disagreement in the garden. DS2 had come in, closely pursued by DS1, who had to be restrained by DH.
DS1, whilst restrained swore at DH, told him he hated him etc (he doesn't they are very close) and at some point kicked DH in the back. (I'm not sure how that happened)
Apparently the disagreement was over DS2 not riding his bike around the course they have set up in the garden in the right direction, causing DS1 to have to avoid crashing into DS2.
DS1 didn't actually hurt DS2.
DH sent DS1 to his room to calm down. About an hour after this happened I asked DS1 to appologise to DH. DS1 said he wouldn't, and that he didn't care. I firmly said "then maybe we'll have to think of something to make you care"
I'm not sure what I met by this, but it sounded authoritarian at the time.
Then an hour later, I told DS to apologise to DH, which he did. I also took him aside and told him DH loved him more than anyone else in the world, that he would do anything for DS1, that he has done XY and Z (swallowed a huge amount of pride) to make sure our house wasn't reposesed, and made sure we didn't need to move. (DS1 has moved 5 times by the time he was 8, and we have promised him we will never move again) And that DH would walk over hot coals for DS1. If there was a fire in the house DH would save DS1 over anyone else. (Obviously DS2 couldn't hear this)
I also told him he needs to control himself, and that he must never behave like that at school as he will be excluded. Which is something which MUST NOT HAPPEN because the school he goes to has pastoral care second to none, and it is by far the best school for him in this area.
So, I'm aware I didn't handle this very well. 
I've probably done a pretty good job of fucking my son up in one evening. And the look he gave me was of pure hatred.
If you've got this far, well done and yes I have name changed. So what the hell should I do next time he behaves like this? (It's not the first time, he has always had behavior/anger issues)