It sounds like you are both willing to work on this relationship problem which is wonderful. No one can fix this but the 2 of you.

Something I learned in a conflict resolution and communication workshop at an old job is to set "conflict ground rules". At a time when everything is calm and ok, decide together what the boundries are for discussing the conflict. You have a good start in using the speaker and listener roles. Based on the change in how things went in your last talk, you can add other rules that you agree on. For example,, I have a conflict rule in my house that eye rolling and other judgemental type gestures aren't allowed.

Once you both know what causes the other person to react in a non productive way, work together to stop pushing each others buttons by accident(I hope neither one of you purposely pushes the others person's buttons) Only she can tell you when you've pushed too far and vice versa. Be patient with one another as you work through things.

Good luck to both of you.