Can long term opiate use cause depression? I've taken tapentadol 150 (2x /day) and opana 5m (1/day) for ~3 yrs, and have been depressed 9 mos. Doc says they may have changed my brain chemistry?

Yes, possible. Yes, long-term opiates can lead to depression. At the very least, your brain and body are habituated to opiates, and tapering will be needed if you ever decide to discontinue them. Adding alcohol to it doesn't help either. It can disrupt mood all by itself.
Opiates ; Addiction. Yes. The simple answer is yes, absolutely. Drinking alcohol while on opiates can increase this effect. Alcohol, as a drug, is known as a depressant. Drinking alcohol when on anti-depression medications defeats the purpose of the medication and they do not work well. The addict brain leads one to despair, depression and death. I would encourage a sincere look at stopping the drugs and alcohol.
Not simple answer. Chronic opiate rx (oprx) for chronic pain (CP) causing depression (depn) after 2 years? Oprx or CP can induce depn; CP is more probable 40-60% than oprx 17-40%. Oprx may impair ovary ; adrenal function, ; cause depn. Other sources? What are fx of failed surgery on role/work function? Why need the surgery initially? Prior / family history depn, anxiety, cp? Note: depncp.