Ex-friend trashtalking me on facebook? What to do?

[Valkyrie]

Sounds like he's feeling very bitter because you didn't reciprocate his feelings. Perhaps you should have been more honest, when you said you liked/loved him, you should have written 'as a best friend/brother' so he wouldn't misunderstand. Surprisingly, guys can over analyze certain situations like us girls do too. From what you've written, he is either insecure or immature, maybe both. But the best thing to do is to be the better person and step up, let him trash talk. You cannot please everyone, it was also wrong of him to keep insisting for you to both date - which in my opinion, is not fair in any friendship/relationship, neither should feel obligated to do something because the other insists.
Carry on dating the guy you're with now and see if it works out. Hope you feel better