vbab, sorry you are feeling like this re DH
I wish I had some advice for you, but like you wouldn't even know where to start. I do know however, that being a single parent isn't the end of the world, and is doable with lots of help if you need it ie tax credits etc. I used to get all my childcare costs covered and I had a good wage (mid £20K mark) as well as money each month from DH (or ex DP as he was then). Emotionally, the DC will cope better than you think; they are both young enough to adapt well to whatever situation they are in, and some might argue that two stable homes are better than one unstable one.
you seem to have been unhappy for such a long time, maybe a trial separation might actually be good for both of you to work out what you both want.
It's not easy to talk about things online, especially on an open forum like this iyswim, but I'm happy to meet up for a coffee and a chat once I'm back from my hols if you like. Pity on the timing though, as I'm too busy this week and then off for two.
ikwym about the raising kids and no "us time" though; DH and I are little more than housemates at the minute, and I don't know of it's to do with BFing and being pawed at by children all day, but I just want to retreat into my own little space after the DC are in bed, and there is just no room for DH in there....he is very patient thankfully, but his (infrequent) mild digs about getting "his" boobs back get met with the contempt they deserve!!
{{{{hugs}}}}}