I'll respond this way. I can look at all the words like depression, surgery, pain, powerful drugs with a long history of bad things. I've had experience with all of it going back to the mid nineties. Now in my 70's I am realizing how I've been experiencing side effects that I didn't know I was having until I started really looking for them. The first was hoarseness. Very common.
Ive had many surgeries, some life saving. Four years ago I had my second major spine surgery that hasn't worked out. The Oxycodone helps the pain but chips away thinking and feeling. I stopped the Gabapentin after a couple weeks. The side effects were worse than without it. Tomorrow I have my monthly pain management visit. I've cut back on Oxy and I'm having shots in my back. I haven't had any since the last operation but I realize I can't take all this meds shit much longer. It's easy to get lost in the medication world. I've been doing it for decades. I don't know how old you are, but the sooner you don't take things that effect things like sex drive, weight gain, anger, fatigue and more, the sooner your life will begin to feel like it did before you had the pain. As far as depression. I had a therapist for over thirty years and took some pills for that as well. He was the answer for me. The pills I stopped so long ago I can't remember the story. Good luck my friend, it might be a lifelong trip you're on. Just don't give up on reading the side effects and looking at where you are. Be honest to yourself.