First, I'm very sorry you have to deal with such a difficult issue, and I'm glad that something is available to help with your pain. It is very unfortunate, IMO, that many people are having difficulty getting the pain meds they need due to the drug war.
I think issue with Fentanyl is not the accurately labeled stuff you're getting from the pharmacist. The issue is that since fentanyl is a lot stronger than other opioids, and is easier/cheaper to manufacture, people in the black market have figured out that they can sell counterfeit pills/heroin/etc. that is actually (cut/diluted) fentanyl, and get the benefits of 1) higher profit margin, 2) easier supply chain (no pill mills or poppies needed), and 3) easier to smuggle and store raw product, due to the higher potency. The problem comes when the counterfeit product is too strong -- a user takes what they believe is their normal dose, but it's a lot stronger and they die (e.g. Prince: http://www.bbc.com/news/world-us-canada-37151146).
I've heard it theorized that the high number of recent fentanyl-related overdoses could be because some gang(s) might be trying to figure out the optimal ratio of fentanyl to filler to use in their counterfeit products by watching the overdose rates in low-income markets before moving the counterfeit products into high-income markets (i.e. they don't want to have a rash of stock brokers overdosing).
Applying Hanlon's razor, another explanation might be that these counterfeiters are just mistakenly putting to much fentanyl in the mix.
I assume that fentanyl is no more dangerous than any other opioid when the dosage is correct (I really have no idea, someone correct me if I'm wrong here!).
(EDIT) The counterfeiting issue is a one of the reasons that some people (myself included) argue for legalization of all drugs or at least better harm reduction strategies for addicts: purity, dosage, and quality control would all be better if these drugs were obtainable from more reputable sources.
Unrelated to fentanyl in particular, but a word of advice: if you need to take these meds for an extended period of time, be very wary of any issues with your gut! A very close friend of mine has been on prescription opioids for around 8 years due to some chronic pain issues she has resulting from giving birth; the constipation side-effect eventually caused a bowel obstruction which she ignored for too long, and it has escalated into a very painful and dangerous situation for her, involving several procedures which sounded very unpleasant.