Hello Slice. You know how annoying it is when people say: 'I know how you feel'?
Well I know how you feel as do all the respondents on this thread. You are not alone and the emotional worst is probably over. It takes courage to end a marriage but now that it's done, you can can look forward to a brighter, happier future. It's amazing how much we can subsume ourselves/our own needs/tastes/ambitions in a marriage we thought was happy - how much compromising we end up doing.
My marriage broke up after twenty years leaving me with two DC's and I felt a huge failure, sodden with guilt and shame (even though it was mutually decided we should split). People I thought were friends took sides and melted away because they thought my 'failure' was catching. A breakup of a couple where there didn't seem to be A Thing to blame the breakup on eg infidelity or alcohol, terrifies some people. If you and DH could split - then maybe they could too. I also found that a few of my female friends started to act like I was some lustful harlot out to seduce their fat balding husband. 'Jokes' would be made about me being 'on the loose' like Anthrax or something. Saying: 'I would rather eat poo on toast than shag your repulsive husband' seemed ill advised so several so called 'friends' disappeared.
Even if you can talk over the finances with your ex, get professional advice to find out what you are entitled to. Check your credit rating - you don't want to be carrying his debts
But I can safely say that after three years, my children are both fine and if they weren't I would know all about it. My parents stayed together and were miserable. I was brought up in a tense and angry house, seething with my mum's contempt and disappointment with my dad. I was too young to understand it but I felt it. It was like a fuggy duvet, and under this, I became an intensely hyper vigilant child, unable to trust my own feelings, and thinking that everybody else's feelings were more important than mine. I had no words for the atmosphere but it poisoned my childhood - dad's alcoholism, mum's anger and bitterness. But they 'stayed' together.
As Todays said, All the Decisions are Yours. You may make wrong decisions but you will also make a lot of right ones, and you have already made the most difficult and courageous one. I was always a bit lazy about car maintenance and odd jobs and despite us both working my ex did all the 'manly' jobs round the house. Not his fault - we just fell into a pattern. Now I take some pride in being able to change a wheel and unblock a drain.
Remember that it's not the break up itself that hurts children, it's the anger, any sense of having to choose sides, and being leant on too heavily by the parent. Relate offer free counselling for young people aged 14 - 25.
My Ex is a far better, more involved dad than when we lived together. He never took them to the dentist or optician or read to them. He does now - at first I think because he wanted to be 'good' daddy but now he does it because he wants to.
Despite working hard and looking after the kids, I seem to have far more free time, and head space. My ex hated me working in the evening, despite him having a 9 - 5 job and me being freelance, working funny hours.
Enjoy being single. Spend time with you and the children.
It sounds cheesy but find something to do that helps you discover and define the new you. A book group or some volunteering, or a course in being a stand up comic.
I'm never lonely. I always remember seeing a poster advertising Relate and it showed a married couple both at the far side of the double bed. The tag line focused on the gap between them and read: The Loneliest Place in the World.
I think it's true. To be in a relationship that isn't working or where you feel unappreciated or neglected is 100% worse than being alone. And women are still culturally encouraged to pair up, to 'tame' the man, to feel validated by being chosen.
Keep a journal. When you look back a year or so from now you'll be amazed at how far you've come. 
