We've been together for more than 10 years and the single most important thing is communication.

As others have emphasized, focus on improving how you communicate with each other. Always assume good faith from your partner, and in turn, always speak in good faith. If you're feeling emotional and you're worried you might say something you shouldn't, then just say you need a minute, and take that time to settle down and figure out how to communicate what it is you want to say. Be patient with each other, and if she says something that makes you upset, understand that she made a mistake with communication and didn't intend to attack you.

If this doesn't work and there's some other underlying issue, then it'd be good to share what that issue is with each other. For this, you might want to consider a mediator of some sort.