it's perfectly normal to be jealous..
it's taken me since october to get over my ex.. (granted, i was still seeing him/sleeping with him until feburary) but to be fair, he's now with someone else, and for some reason, that's just caused me to not give a crap about him anymore. him being with someone else has shown me that he has moved on, and it's given me closure. i was wondering 'what if he wants to get back together' for ages, but now i know we never will, it kind of feels great. it's like a great weight has been lifted off my shoulders.
plus, i've found someone who is a million times better than my ex anyway. i'm glad things happened the way they did.. i learnt so much from that last relationship and now i know how to make a relationship work. i thank him in a way.. i hate him for what he put me through and for lying for so long (saying he loved me.. jackass) but now i know i'm so much better for it.
i think it just depends on you though. if you can let go, move on and find someone else, the easier it'll be. for me, i saw the picture of him with his new whore (lol) and from that moment, life became that little bit easier.
of course, there is always going to be a little part of me that hope he ends up alone and such, but he was a jackass.