I love seeing WI and AM aroused and alive and immersed. Totally turns me on. WI experiences the same with AM and me. And AM with WI and me.
I think your experience is awesome -- if it's what you're feeling, feel it! You love it when your husband is in love and making love. That is incredible. You're an amazing human being.
What should you do? Enjoy it. What's about this: Join it? And if that has no appeal and you are at peace being the watcher and enjoyer, then feel safe. You sound happy. Don't second guess. Just be happy!