:) I can’t quite recall the poem you’re talking about. Would it happen to be either of these two, by any chance?
http://writingsforwinter.tumblr.com/post/44832861476/addressed-to-the-woman-who-slept-with-my-boyfriend
http://writingsforwinter.tumblr.com/post/44593202763/for-an-ex-lover-becoming-someone-elses
Do you remember anything else about it that might help me find it? :)