anxiety is a very vague term used more or less to sell pills. Benzodiazepines work well for short term anxiety, but should not be a long term plan. Same goes for booze... Say your house burns down or something, a weeks worth of benzos, possibly less, would be perfectly appropriate.
Long term anxiety is likely some sort of maladaptive feedback loop which i'll spare the technical details of, but there currently isn't any reliable medicinal treatment for it that doesn't cause addiction. The most extreme form of chronic anxiety, PTSD, currently has no widely used effective therapy either. Cognitive-Behavioral Therapy (CBT) is somewhat effective, but extremely unpleasant and can do more damage if it is not effective or the patient doesn't stick with it. Eye movement desensitization and reprocessing (EMDR) is also somewhat effective and I'm anxious to see more research on it, but interestingly enough MDMA therapy seems to be among, if not, the most promising of therapies. Granted it only uses 4-6 doses a year, but that's really about all one should take anyway.
You say you know from personal experience that every dose does damage? Have you had any tests done to confirm this or does it just feel that way? Either way I'm sorry for your health issues, but pure MDMA in reasonable doses no more than once every 8 weeks or so shouldn't really do any appreciable damage. Its entirely possible you had some combination of all but unstudied pipazerines and god knows what else if you bought pressed pills, and even given the relative safety of MDMA in a controlled setting, idiosyncratic responses are possible and will likely occur at some point. Furthermore, every drug is a risk/benefit type of situation, whether licit or otherwise.
I've seen much more problems in peoples lives arise from benzo & opiate usage than I have from MDMA, in fact out of the many many people i've known that have taken MDMA, I can only think of 3 that have had some issue with it, and one of those was a very chronic user for an extended period.