Taylor Swift has some advice for her ex who inspired ‘We Are Never Ever Getting Back Together,’ as well as a timetable for when you should get over your former flames.

How long is too long to get over a lost love? Swift pondered, “I think it’s double the amount of time you were with them. For me, just take the amount of time you were with them and times it by two, or seven.”

Swift admitted that this song came as a result of running into a guy who knew an on-again, off-again beau. “Well I wrote this song with Max Martin and Shellback, which didn’t hurt at all. This actually happened,” she began. “When we were in the middle of writing a different song and this guy walked into this studio randomly and he’s like, ‘I’m friends with your ex-boyfriend. I heard you guys are getting back together.’ But as soon as he left, I just started going on this rant. So Max said, ‘You seem really passionate about it. You should write a song about it.’ We just created this song in like 30 minutes. It came from a very real place and it came from a very spontaneous situation.”

Swift also revealed that she has a duet with her “absolute favorite band” on ‘Red,’ but she wouldn’t say who — though she admitted that she’s “most excited” for that track. One thing her record is missing? Hip-hop features, which she says may come on the followup to ‘Red’ so she’ll have room to grow.

Watch Taylor Swift Talk About Her New Record + Getting Over an Ex