Morning Penny, I was burning the oil last night/morning and was following your thread.
I understand totally how you are feeling and I don't want to sound as if I'm underestimating how devastating this must be for you right now while it's all so raw and fresh - but you've got so much going for you, honestly you have, even though it doesn't feel like it right now.
The first thing that comes through in every word you write, is that despite the turmoil you are in, you are a very capable and practical person, with a great deal of inner strength. That will help you enormously in getting through this.
You are also young - just 27, you own your house outright and you don't have any kids with this arsehole. For a lot of us, we were much older, had kids and the house/assets situation was far more complicated. And we all survived and many of us have gone on to far better lives than we had when we were with our exes.
You won't have to give him half of your house so don't worry about that. As others have said - see a solicitor asap, and as of now start writing absolutely everything down, keep a diary, and keep every bit of evidence, emails, texts, everything. Your husband is an adulterer in the eyes of the law.
As for the heartbreak aspect of this, so many of us have been where you are right now, but as the days pass, I promise you - you will soon come to see what a total twat this man really is. He's nothing but a knob on legs, who has cheated on his wife with an 18 year old. She's barely even an adult. It looks pathetic to anyone outside looking in, and that's because it is pathetic. He's pathetic ... and you'll start to see that yourself soon enough. One day, not too far up ahead you will look back and wonder what the hell you ever saw in him, even that sounds impossible right now.
If you can't eat, sweet milky drinks work a treat. I lived off hot sweetened milk for about a month after I finally kicked the fat bastard ex out. Lots of lovely warm baths too. If you are feeling anxious or agitated and can't relax, just go and lie in a nice warm bubble bath. it really does help get rid of some of the tension. I was having about six a day at one point haha!
You are going to get a lot of crap and excuses and blame and allsorts come at you, so be prepared. They are masters at twisting the truth and there's a well-worn script that gets followed. The phrase 'rollercoaster of emotions' couldn't describe it better. You will go through everything from despair to anger and back again. Remember though, that no matter what he says, none of this is your doing. None of it. Keep that in mind at all times, whatever bullshit he comes out with.
Good luck sweetheart and know we are all here for you.