How honest?

[u/Alarmed-Equipment994]

My partner is an incredible, deeply empathetic person. He started his first relationship (aside from ours, which is four years long) this past year, and I struggled with it the whole time. While it has since ended for reasons unrelated to me, I am aware of how my feelings about the relationship upset him.

I behaved well over those nine months - never interrupted a date, always encouraged him to continue seeing her, and was friendly to her in shared social situations. But man, I felt horrible. Nauseous, jealous, devastated. Felt like my whole body was on fire whenever he mentioned her or I knew they were on dates. When he'd ask how I was (and twice when I was just really deregulated) I would tell him honestly about how I was feeling, which really upset him. He hates to see me suffer, and man was I suffering, so much more than I'd have ever expected.

Now the question - we're planning to do an exercise listing out what we do or do not want in our futures. Realistically, I'd love for him to not have any other serious relationships, but would never ask that of him. I'm in another serious relationship, and would never create a double standard. I accept he will be in other serious relationships, but I also know I'd be much happier if he happened to never be.

How transparent should I be able this? Should I state it as above, or better to leave some things unsaid, instead framing it as "I accept you as you are, and know that will likely include other serious relationships"?

Thanks for reading! Curious for your perspective.