Ecsatsy Rising hosted by Peter Jennings is an unbiased, truthful look at MDMA that has helped open many of my friends and families minds, it's also entertaining so you'll likely get them to watch the whole thing:
http://www.youtube.com/watch?v=K0GG4U_d28k&feature=fvst
Unfortunately, we live in a world that puts a label or stigma on so many things- if you tell your friends something new about you (I'm gay, I'm muslim, I like lsd, I like weed, I'm bi) there's often a judgement placed on it. Though it's been proven false data for a decade, many people still site improper MDMA research that claimed that it caused holes in your brain and Parkinson's disease.
Often times, when I meet someone else in daily life (or even at a club/rave) who does MDMA they're a successful happy person who doesn't come across as a "druggy", my own dad has been experimenting with drugs all his life (he rolled with us just last year) and he's extremely successful in his field of work, with no cognitive issues.
In terms of dealing with people, you have to formulate your response so you don't seem defensive- explain to them if they are truly concerned you'd really appreciate them watching the Ecstasy Rising special because it explains a lot that you can't. Explain to them that MDMA is not the sort of thing that you do daily- it's a special occasion experience that you indulge in once a month (or however often you wish to say). Invite them to check our erowid.org as well, and explain that MDMA is not disrupting your life, but rather an occasional enjoyable experience you indulge in. You can also find lots of information on it's therapeutic use, there was an article in Oprah's magazine on it (with a photo of the author looking very clean and professional

)
http://www.oprah.com/health/MDMA-Therapy-Jessica-Winters-Report-Ecstasy-and-PTSD
I share your pain with this issue, as when MDMA was new to me, I wanted to share how much I had benefitted personally from it with everyone. Trying MDMA was one of the best decisions I made in my life, however, to tell friends who haven't experienced it that- you just sound like a crazy person in love with drugs from their view. Do your best to keep your composure and refer them to some "official" reports like the ones I gave you, as in these situations, you really need an outside voice to explain your case.