So he cheated on a previous partner but minimised / lied when you spoke about it previously?
I think it's down to individuals what they can cope with so only you can decide if you can / can't move past whatever you've found out.
What I would say is, from the way you speak about the relationship it does sound codependent. I know because that sounds negative you probably feel defensive about it.
But it's taken me years to realise that codependent relationships are not healthy. When I've said in the past that I couldn't live without a certain person / could never love anyone again if we split / can't be myself with anyone else etc it's ultimately been an unhealthy relationship.
In a healthy one you love the idea of being together forever, would choose that if life was black and white, know they are your favourite person BUT also know that you could cope without them if you broke up.
I hope that makes sense. I have bipolar. Have always been in very intense, unhealthy, us against the world, nobody understands our love type relationships until fairly recently, after a period of being single and focusing on myself.
Counselling and medication have changed my life. I have a healthy relationship now - I love my partner, have healthy boundaries and while he's my favourite human and I would love to be with him forever, I know that sometimes life throws curveballs and if we weren't together I would be just fine.
True love is, for me, wanting someone not needing them. It means more. You're choosing them, not relying on them.