I would tell your mutual friends. But not post it on facebook. I dont mean this in a rude way, just trying to be direct. People who post details of breakups on facebook arent viewed as stable. I think that you are stable because otherwise you wouldn't be pondering whether or not to go online with this. Do you want a guy who might end up being awesome for you to date seeing you post this? Think about who you represent in this world-yourself. Don't represent yourself as being unstable. Now, sending a PM or text about the situation is fine. I would try and sound more matter of fact than livid in my tone with that too. I'm really sorry this happened. You are now free of two major pieces of baggage, though.