Then I am glad the past is PAST. And that you both are moving it forward in a way that encourages better communication, trust, and openness. Read together, learn together.
Figure out what you rights and responsibilites
might look like (I link to mine) and how you will deal in conflict resolution.
If you are USA, sometimes county extension offices have a lot of relationship skills classes and/or handouts like healthy conflict resolution. Google the name of your county and "extension office" to find their website.
Like "Apple County Extension Office."
Sometimes churches offer relationship classes or curricula to strengthen relationship. Though not necessarily couched in terms of poly, communication skills are communication skills. YKWIM?