it was chatting and some dates that instead of him bringing up to me he his (hid?) til I found out by accident.
So... did he break the agreements or not?

Before all the poly talks, were you Closed? Going steady? Exclusive?
Or was it not exclusive, but you didn't call it "poly" necessarily?
Because if his behavior broke agreements, it broke agreements. Whether or not you use the "cheating" word or not. Before you move on to new stuff (like making new poly agreements) you two could clean up the old stuff first. (like account for and reconcile broken agreements.)
Otherwise you are going to have a hard time believing in his Word, and believing that he's making new agreements he intends to keep now. Id you cannot trust him to keep his Word, then he isn't trustworthy.
If he broke agreements and dinged you? But is not owning his behavior and cleaning up his mess? I'd be leery of making new agreements with him and maybe getting dinged again. Who wants more dings than necessary?
Your consent to participate in things always belongs to YOU. You have a say in what you do.
- You can choose to participate in in a relationship with him or not participate in relationship with him.
- You can accept the dating offer he is presenting to you or you can decline the offer.
- You can choose to be in the "potential ding zone" where his behavior can affect you. Or you can get you out of the zone and then whatever he does, it doesn't affect you.
If you don't feel good participating here with Phone Woman in the new poly network, speak your truth and let the chips fall where they may. If he's hell bent on going there? You don't have to go too.
Galagirl