"I'm sorry. We had a disagreement and both of us made a bigger deal out of it than we should have. I know you've been waiting for me to make the first move, and I've waited for you. But instead of the tension, I want healing and will work for it. Our relationship is too important to play guessing games. So whether or not you want to work on this or even see a problem, I want you to know I do and I'm not going anywhere. I'm giving you the gift of choosing to not hold any of the past into our future together. The door is open and will stay open - let me know what you think our next step is. I want to take it with you."
Feel free to use that with "you know who" in a phone call, email, text, or Facebook note. Your pick.
"Forgive your brother from your heart.” (Matthew 18:35b)