Hi OJ!
They're all right, you know. I have been pondering on your question for a few days, too, because I have an ex- out there, somewhere, so it isn't the same.
The one thing that keeps coming to mind is that you can concentrate on the kids, you can be child-centred, you can work round them and they usually make it all OK. Get some respite help in place, if it is available and when you are ready, look for something that is just for you - a course, a hobby, a class, the gym.
Life is not the same but the love that got you to this point will get you through. Your love for Steve, your love for the DCs and slowly, your love for yourself for surviving, for doing the best job possible and carrying on.
I have a wish-list of things to keep me going: most include trying new things, going places with my DSs but some are just about me, some will never happen but you never know.
Take care. Keep talking, both here and in RL.