It depends on what YOU need. In my case, my fwh is anal. So I asked for every date, hotel, dinner, gifts, and what happened in each. With the stipulation, if he left anything out intentionally, he would be sitting on the curb. It took him a while, but when I made my line in the sand, made it clear she could have him if he wasn't capable, he complied. He was also surprised and ashamed of the time he took from us for his fantasy life as he convinced himself and told me "it wasn't that often/much". We were both surprised, (I was stunned), but knowing helped me begin the healing road. That and his actions each day since.
Ask for what YOU need. You will know deep down if it's the truth. I think we, some of us, get an extra sense after this. My fwh had to also learn that an omission was a lie. Black & White, not gray area.
In R since shortly after DD.
Discovered what was right in front of him and nearly lost.
Always, tell the other BS! Always!
"It's hard to be in love when you can't tell lies"!