Hi everyone. I'll try and condense this to make it easier to read so please understand if I miss things out.
My husband and I have been married for 10 years and we have 2 children. For most of the time he's loving, works very hard for us and is very generous.
However, he is also very moody and snappy often and sometimes he shuts down completely. Yesterday for example ... my 7 year old son is very very disorganised, has selective hearing and yesterday he did a minor thing wrong and I got cross (a culmination of me being irritated about his absent mindedness) I wasn't shouting or anything but my reaction was, I admit, disproportionate. At this point my husband started to get angry too and was saying "yes yes DS, you're completely retarded. You're an idiot" etc and it went on until my son started to cry. I asked him not to call him that and so he said OK he'd call him an RI instead, meaning retarded idiot. We had to go out and we got in the car and it continued. I snapped and said please stop saying that to him and he then said that to be honest it was me he was annoyed with because I was too cross with DS over this minor thing. I asked why he felt the need to upset DS more and why he hadn't just taken me to one side and say that I was being too heavy handed. He said because he felt it would make me stop (??) and I wouldn't have listened anyway (I think that's unfair - I always take any criticism from him in, listen properly and try to change, especially if it involves the children).
Anyway, he basically ignored me for the rest of the day after he had his outburst in the car, I usually retreat to the utility room when he's in one of these moods and I did most of the outstanding ironing. From time to time I was crying (I know it sounds pathetic but I can't describe how bad it feels when he shuts me out over a minor disagreement) and he came in for something and saw me. He asked why the hell I was crying and I said that when he's like this I feel crushed. At this he burst out laughing a d said scathingly, "crushed! I'd split my sides laughing" and he walked out chuckling. He carried on the silent treatment and we went to bed on bad terms. It continued for the rest of today, Sunday, and in the afternoon he asked what I wanted for tea. I've been dieting recently and really fancied some KFC, so I said KFC please. He walked off wordlessly but we home cook most of the time and he really loves having a take away normally.
Later on he asked my son what he wanted and when he got a reply I heard him say "Hmm maybe I'll make some pasta". I knew this was my 'punishment' so I ignored it and got up to make pasta (to appear unconcerned about the KFC). At this point my daughter (9) said aw can't we have KFC and I said no, daddy would like something home cooked. He then realised his chance of KFC was slipping away and tried to back pedal saying he didn't really mind, but I pushed on with the pasta, knowing that my not coming into the room to ask why we weren't having that would ruin his attempt to upset me. I made the pasta and the 3 of them ate it, with him getting irritable about tiny details. He said "for fucks sake" at least twice under his breath and did these incredibly deep sighs that he does when he's in one of these moods. It's such a deep sigh that even when I'm in another room it turns my heart to hear it.
We eventually went to bed and he said "sleep well" then turned over to sleep. So now I'm in bed typing this in turmoil, while he sleeps deeply.
This is one example. Most of the time he's caring and tells me he loves me several times a day with hugs and kisses but these huge silences happen from time to time (the last one was last weekend, but before that a while ago) although he often (daily) snaps at me for not much, even when things are nice. He's quite stressed with work (we run our own business) and I'll ask a simple question and get a really sharp retort. He has tried to address this though and I now say something like, "Wait, why are you replying like that?" and he'll usually rephrase it to sound less harsh.
It's hard to describe, but I feel totally abandoned during these phases. It's so hard to cope with. In a day or so he'll be poking me and saying something like "don't be moody" and "cmon, love meeee". I always give in because I want things to be nice and if I try to post mortem it too much, it'll lead to a huge silence like this weekend. So I have to just leave it.
But I'm tired of walking on eggshells. I probably start most days that hes home with a lump in my throat because of something he's snapped at me over. An example is that last weekend he did the usual pokey jokey make up thing and I tried to deal with what had happened. So I said that I wanted to be friendly very much but I didn't want him to trivialise what he'd put me through all weekend. He tried a bit more and repeated the trivialise thing to which he suddenly turned from his smiling self, said "prick" and stalked away from me. This prolonged the silent treatment even more, so normally I just accept the attempt to 'make up' but I'm left feeling like crap inside.
It's just that I can never be cross with him for more than a few seconds or it'll turn into something much more, like this weekend. But he feels able to be cross with me whenever he feels like it.
There's no question of an affair and that's certain, I promise you.
He often acknowledges that hes stressy and says he'll change but he never does.
I just feel like walking out and never returning.
I don't know what to do. I'm writing this now because I can't sleep and meanwhile he's sleeping deeply next to me 
So sorry for the long post and thank you to anyone who read it all!