they talked it out when they broke up in the prequel. yumi actually forgave him immediately. right now this is completely his own internal struggle because the only who's really mad at him is himself
No, they did not talk nor seen each other since Kan told Yumi to leave him before he hurts him. Yumi never said I forgive you or anything like that. Its been a couple years since then and they haven't ever said hello to each other. Yes, he is having an internal struggle but sometimes communication can remove scars. Yumi seems to be doing fine, Kan iss another story. He needs to talk to Yumi, even if Yumi doesn't forgive him (I'm prety sure he does, given that Kan was severely abused at work), he still needs to talk to him. It's called closure.
Hayashida's character development is remarkable and excellent. I believe that people are capable of change, if they want change. Hayashida is still somewhat punishing himself, he is more open but not completely. I hope in future chapters he meets Yumi and they talk it out. They are both in really great places and have great love and support in their partners. It is truly wonderful when a great yaoi has a great story as well. And Hayashida gets more handsome each chapter