AIO for being upset

One of my best friends is also my ex boyfriend. We ended the romance part over a year ago but besties ever since. I recently ran into his buddy who told me they havent been friends in over a year because my friend was secretly hanging out with his wife. I had no idea. To the extent of what they did together is unknown but his buddy found secret texted of them saying how they wanted to be together. Putting the pieces together, this was happening while in a committed relationship with me. Now mind you it was over a year ago and im just now finding out but it still stings and hurts so bad. I think if we weren't friends it wouldnt matter. I blew up at my friend and didnt get a ton of responses but overall said he didnt mean to hurt me. I havent spoken to him since which was about 3 weeks ago. I do miss him and our daily friendship. Do I forgive and reach out to him? Give it more time to think if I want him in my life or wait til he reaches out?