His ex-W was suspicious, my ex-H was clueless. However neither found out definitively about the affair. My now-DH told both when we officially got together, two years after I left my ex and 18 months after he left his.
I left my ex first, and ended the affair shortly after because DH told me he wouldn’t leave his wife. I knew I wanted kids and wasn’t prepared to waste time. I also suspected he was a little too
comfortable living with having an affair, and wouldn’t make any changes unless I made it clear I wasn’t going to be the OW indefinitely.
If by full relationship, you mean turn it from affair to marriage, babies etc - within weeks we were lamenting the impossibility of that ever happening (yes it was all very angst-filled!) I think I slightly led it at first, but also dramatically ended it every few weeks/months while he clung on. It was exhausting tbh, I sometimes think I wouldn’t have an affair again simply because I don’t have the energy!
We tell people a version of the truth, just omit the part where we had an affair. We knew each other for years. We married other people. We split up with them. We have an “official” start date which is when we actually did finally get back together, post affair, post all breakups.
We would meet probably at most twice a week, at its most steady we rarely went longer than 10 days or so. We had lots of mutual friends so saw each other naturally that way, although obviously couldn’t be snogging then (although we were less subtle than we should have been when our spouses weren’t around, and definitely raised some eyebrows). On our own we would mostly meet in public. We used to have a regular date night at a pub quiz, as bizarre as that sounds! Some rolling around in parks like a pair of teenagers. We booked hotels every couple of months - he travelled for work so it was easy to extend a trip by a night and my ex was completely incurious about where I might be going.