When my wife was in rehab, we had a couple of joint sessions with a counselor. With a referee in place and some gentle guidance, we had the first "honest" conversation that we'd had in a long time. No a long conversation, but honest things were said.
Afterward, I spent the night feeling highly anxious. I took the counselor aside the next day and said "I'm afraid that what I said to (her) broke her." The counselor just laughed lightly and said "You can't break her." To me, that was an epiphany...like, duh!
I totally get that feeling of walking on eggshells. Three years into recovery, I can't say that I feel completely free to speak my mind, but I can and do speak my mind and that's a better place for me to be.
I used to feel defensive all the time. My ego and my wife's ego were firmly intertwined. A zig on her part always resulted in a zag on my part. If she was up, I was up. If she was down, I was farther down. (At some point I realized that I'd made my wife my higher power).
I don't know how I learned to detach, but I did. I do know that Al-Anon played a big part, but I'm not saying it's simple or easy, I just know that if I hadn't learned to detach I'd still feel pretty crazy most of the time.
Now, if she feels like crap, I can commiserate, but I feel no need to fix the situation. I'm not responsible for her happiness (and she's not responsible for mine). Instead of feeling defensive, I can just listen with compassion. I no longer have to react.
Reading what I wrote, it sounds kind of selfish, doesn't it? I think that recovery is fundamentally selfish--we "fix" the only person we can fix, ourselves.
I realize I'm not offering advice, I'm just sharing my experience and hopefully the idea that our relationships can get better. (And "better" can take a lot of different paths).