I'm new, married, extreme sexual anxiety/depression that I do not understand.

Hello,

I am hoping to talk to some people in regards to severe anxiety and depression involving sex. Long story short, my wife and I explored a non-monogamous lifestyle for around 6 months. We have been married 8 years. The idea was originally mine, I am bisexual and wanted more experiences, however as time went on I found myself more and more uncomfortable. I could not quite pin down why, I gave a lot of reasons and excuses that I am not sure are true anymore. Roughly six months ago things came to a precipice and we stopped the lifestyle on my request. My wife and I had some disagreements and some hurtful situations happened as a result in which she was non-monogamous without me. As time went on I felt guilty and shame in the actions we had taken, I began to feel that sexual experience should not be so casual and should remain private. My wife does not agree, she is much more open and came to enjoy the lifestyle tremendously
Within the last month or so I have become insanely anxious about sex. I cannot seem to see it talked about on TV or in a song so casually. My body becomes physically ill and tense on the topic of sex. There was a comedian on TV talking openly and proudly about their sexual encounters, or people (men and women alike) proudly calling themselves sluts.
I legitimately do not understand this, or how this is something positive. I come to find I have a tremendous amount of shame about sex and I do not know where it comes from. Society and my mind are telling me I should not have issues with sex, be sex positive, support my wife's wants and needs, and be open. However the physical feelings in my body make me feel that sex should be something special between two people, an action of vulnerability and trust, that it isn't right in the slightest to be so casual about sex. I have never understood one night stands or hook-ups, and I have issue even hearing the topic mentioned in passing now.
I am not sure how to move on or recover. My wife wants to be able to explore her sexuality, but I cannot mentally handle it without seemingly losing my mind in a downward spiral. In these moments I feel that I should be enough for her and the fact she sees sex so casually will hurt me extremely deeply, it makes me feel like I am nothing special.
I have the conflicting views that I wish my wife only wanted me, yet I know that isn't reasonable, yet that is how I feel about her so I know it is possible. I just need to talk to people about this, I love my wife more than anything in this world and I do not know how to get through this.
Thank you.