<human>: Could you distill the essence of the text into 1-3 sentences?

My whole friend group communicates in a Facebook chat. We are all really chill and have a dark sense of humor and no one real cares what we say to eachother. So my friends gf posts a picture of her in the car with another guy jokingly I say she is cheating on you. Then he responds by saying not exactly. And then again I jokingly say, "oh so you were cheating on her". It turns out he did and they broke up yesterday. Which I guess everyone already knew this in our chat and other friends started messaging me telling me what happened and how I fucked up and explaining the situation to me. Basically it got really awkward and my friend messaged me like a long paragraph saying how he loved her so much and he wanted her back and it was all his fault. Made it much worse when my friend started messaging me about how he cried in his mom's arms which inturn made his mom cry. As well as bringing up this awkward conversation. I also began a fight in our chat with my friend trying to apologize to his ex gf and her saying fuck you and stuff. 

Really I can't take full blame for this they break up and stay in our Facebook chat as friends like nothing happened
<bot>: jokingly said my friend cheated on his gf in front of her when he did. And they broke up the other day