this sucks... my best friend came to me with this situation and i couldn't find what to say to her because i'm sort of going through the same thing... sort of...

here's the scenario/situation:

an ex-crush/flame who you haven't seen or spoken to in a really long time, with whom things didn't end so well, decides all of a sudden that they want to be "friends" with you again. throughout the relationship or whatever things were pretty intense, but there was always something that went wrong and ended said relationship. now a loooong time later, here they come wanting to start things off again, but you're with someone. your old flame means a lot to you, but you love the person you're with. you seem to be stuck between a rock and a hard place, what do you do? how/what do you say to your old flame?