I had sex with my best friend’s mum at his 21st and think about her all the time
I say that because no matter how you look at it, nothing good can come of this.
I hope you have the kind of relationship where you can tell your ex about this and you both can laugh.
Why do they make a bee-line for me and why do I allow myself to get into this situation? He does intend to leave his girlfriend and has made no secrets about that as he shares it with his family and friends, not just me.
Then the more you should be careful when going into the next relationship.