Ok man, First off Im not going to insult you by saying "I know exactly what your going through". I have had to face nearly dying in a car accident, addiction, a divorce, mental illness , and ashamedly a suicide attempt. What I can say to you is that I know what its like to reach out for help, and how devastating it can be to not get it....
I too used to reach out to strangers in online forums. Its easy since you don't have to look them in the eye and I never felt as judged as I would if I were talking to someone who knew me well. I'ts a great first step, but for me it was just a quick fix. I'd get something off my chest, feel better, and fall back into my old habits in no time.
Since you clearly want someone to talk to who isn't going to judge you and get angry at you... I really recommend getting a counselor. There is no shame in it!
Tell them the same things you told us. Once you understand what drives you to abuse mdma, you can work on controlling and or quitting your usage.
The same goes for your marriage. Tell the counselor what you've done and how it makes you feel. They will help you understand your behavior. I's up to you if you ever come clean with her. Once your happy with yourself, you will be a lot happier with your marriage as well.
Anyways that's my 2 cents. It certainly helped me, maybe it will help you too.
Just remember: It takes courage to admit you need help, and there's no shame in being courageous!