Sounds to me all this jealousy is your own insecurity in yourself. Think of loving others in this way: how can a lifeguard save a drowning person, when they don't know how to swim? How can you love others, when you don't love yourself, first? It sounds cliche', but a wise Indian once told me, "Hey, if it's cliche', cousin, it's probably because it's true".
You can't dump all this jealousy on someone and hope that repeating how you feel will make things better. You both need to stop and realize how your actions are affecting yourselves, and each other. The party story really makes me sort of feel on the side of your guy, because he was trying to say, "See? Things are fun, everything's okay in the world, no need to be upset!" He was trying to share his happiness with you, and your own insecurities overlooked that meaning.
I'm not trying to make you feel guilty, you already feel that, but you need to understand that HE'S not making you jealous. Neither is his crush. YOU are making yourself jealous. If you have no confidence in yourself, you can't have it in others easily. And more frightening enough, your jealousy and insecurity could, in the long run, end up pushing him away.
What I like to do is imagine my husband really enjoying the company of another woman so much, and he's filled to the brim with love, and he comes home, gives me a big kiss, and with a smile from ear to ear, tells me about how he and his lovely new crush had such a wonderful time. I can't tell you how my heart swells at this thought, and I really really really hope you can one day let your love concur your insecurity.