So very sorry. It does sound as if an ow is likely, some classic "cheaters script" comments/responses there, so try to be prepared for that eventuality - as much as anyone can be!
Next most important thing is to prepare yourself legally/financially.
While you have the chance collate as much evidence of all your (plural) finances as you can.
Check on benefits calculators where you'll stand when you do split.
Would his leaving you now leave you more in the shit than if he does so later? Genuinely?
In addition if it's possible for you to be separated but remain living under the same roof you would be eligible for benefits in those circumstances - more common than people realise - but there are rules on this that you must follow.
When my ex and I split I was a Sahm, no income of my own and the split meant losing my home too (ex was army we were in quarters) and I'd no local support network and couldn't afford to go "home".
About as bad as it could be, not going to say it was easy but I did manage with help from ssafa, shelter and my Mp (and a Tory one too!)
You'll be surprised what you can cope with.
And yes beware the attempts at gaslighting and twisting things.
My ex tried to make out I'd turned into a jealous control freak overnight! Totally not my style ever! But I rightly had my suspicions which turned out to be correct.
Even when ow fell pregnant he tried to convince me and others she didn't get pregnant until after we split. The baby's birth and the baby very clearly not being premature put paid to that but he maintained that stance throughout her pregnancy. There was other evidence that came to light too...
He still didn't admit it for YEARS even after we were divorced!
He went nuts when I included her name in the divorce papers! 
but by that point couldn't deny it legally as she'd had the baby by that point and I could have insisted on a dna test and proof of likely conception date had I chosen to.
Don't let him set how things go take control. You'll feel so much better