Basically DS2 (special needs, adhd, aged 12) came home from school full of attitude, ended up arguing with DP, it all blew out of proportion and went too far, DS bolted out of the front door, DP went after him and ended up falling cutting open his hands, legs and hip - result - lots of tension and a very tense and unhappy household.
But DP and I went out as planned (later when he'd had time to cool off and the house was calmer). Went for a meal (lovely) and then met up with friends for a drink in a local pub. everyone having a good time but DP is getting drunker and drunker and by the time we leave the pub for the club, he's switched from lager to whisky - a drink we know turns him aggressive and argumentative. But I watch him carefully, all is ok ... he's having a good time, laughing and joking, dancing, hugging and kissing me - everything seemed fine. Then later on, I'm tipsy too (but he's really drunk by now) I notice he's looking grumpy so I pull the sides of his mouth up into a smile - we always do this to each other and it normally results in the grumpy party laughing and cheering up. This is exactly what happened. He laughed, started pulling daft faces and making "kissing" faces, we were like a couple of teenagers in the dark corners of the club laughing and giggling with one another, he was also poking and prodding my face. All very normal.
Then all of a sudden he turned on me. I can't pin point what made him snap but one minute he was fine and then a split second later he was livid, told me he'd pull whatever face he wanted to pull and that he WAS having a great time until I started "pissing about" with his face. He said he wanted to go home. A little shocked I told everyone we were leaving and we left. In the taxi we didn't speak a word to one another. When we got home he verbally laid into me saying I disrespect him, treat him like shit, obviously hate him and think he's a wanker and he doesn't know why the fuck he bothers with me because I make his life a misery and he's had enough 
we've had NO arguments or disagreements at all lately so this was totally out of the blue. He goes on to say that if his late father could see him now, he'd be crying at the way his son's life had turned out and the family he'd ended up with 
. He starts acting really bizare, makes me a cup of tea and then shouts at me for drinking it saying "what the fuck are you drinking that for?? you hate me remember, fucking put it down!" and then I look at him as he's raging at me and he shouts "don't you fucking look at me!! you couldn't stand to look at me a minute ago so don't you fucking look at me now!" When I speak he starts mimicking me like a school boy, he laughed when he could see he was upsetting me and said "oh don't worry, you'll find somebody else, you'd find some other wanker who'll put up with your shit and your fun house kids - infact, why not go back to the fucking club and grab one of those blokes you were looking at in there?" (not the first time he's accused me of this).
In the end he storms off upstairs saying "don't worry, I'll fuck off in the morning and you'll never see me again".
As I'm getting in bed I accidently touch him slightly and he shouts "what the fuck are you touching me for??? I'm a fucking wanker remember! you fucking hate me remember! don't fucking touch me now!" by this point I'm actually getting a bit concerned and gently put my hand on his shoulder and said quietly, nicely and calmly "D*, please calm down - I don't know what has made you so angry but you're really upsetting me, we never talk to each other like this" he replies with "Oh!! I'm upsetting you am I!! oh dear, I'm sorry, what a bastard I am, I'm upsetting you! oh my god! you're upset!" and then laughs. I said "this is really out of character for you, I'll talk to you when you sober up" he then grabs my hand, pushes it away from him and turns to me saying "get away from me, go on, turn over" and starts trying to push me over. I shout "just stop it now, you're starting to hurt me" and he laughs and shouts "oh come on! fucking hell I better call the police on myself then" and starts a ridiculous routine of him on the phone to the police.
Eventually I snap and say "how old are you? jesus you're acting like a 7 year old. Just go to sleep". He replies "yes I will do, and in the morning I'm fucking off and I can't wait to be rid of you". I cave and start to cry. He shouts "oh fucking hell here we go, don't be fucking crying all night! don't know why you're so bothered anyway, you hate me and I've never loved you anyway" He then starts prodding at me saying "stop crying, stop it" etc etc.
Eventually I drop off to sleep. This morning I wake up thinking "jesus, that was a side to him I never want to see again! wonder what he'll think when he sobers up!" - he wakes up - sober - stares at me for a few minutes and then says "you want me to fuck off now do you?" - Only when I go along with it and say "yes, it's probably best that you leave" does he go back on it saying he can't leave as he loves me too much etc etc. He doesn't apologise but makes excuses saying he'd had a shit day and I was slagging him off too (untrue).
Around lunch time today he finally comes over to me, puts his arms around me and says "I'm so sorry about last night, I was a complete prick and I'm so sorry I hurt and upset you".
We've been together just over a year. I'm in total shock at his behaviour.