Orgy and useless emotions

I'm an actor. My fiancé is an actor. We are aware and understanding that, sometimes, he or I will be cast in a show that will require one of us to (pretend) perform certain acts that conceivably should only be performed between the two of us in the privacy of our own home.

Let me clarify the situation:
My fiancé was cast as an evil spirit of sorts in Opera Lyra's Les Contes d'Hoffman - great for him!

My fiancé has to wear some form of velour and mesh bodysuit that leaves little to the imagination - again, great for him! He used to be a professional ballet dancer... nothing new for him there.

My fiancé, from what he has described, has to move about the stage in a very suggestive and erotic manner - no problems there... he's great at that!

My fiancé has to writhe around on a bed with the other actors - um, ok.

My fiancé has to pretend to go down on my roommate, who is also performing in the show. She also does the same to him - umm.... what!?!?!?

Now, I'm not at all the jealous type. I have complete confidence in my fiancé and in my roommate. I know they don't like each other in that way... but is it so odd of me to be feeling uncomfortable when they discuss the "blocking" of the scenes over dinner? Is it wrong of me to cringe everytime they make jokes?

It's not the fact that they are performing these scenes that bothers me... it's the fact that they keep talking about it and making jokes even though they know I'm turned off by it.

The worst part about this is ... I'm actually going to see the show and witness this first hand!

Actually no, I'm wrong... that's not the worst part. The worst part is that I'll also be sitting next to my roommates mother! I decided to invite a friend of mine along, someone who knows her and him well, and who is great at poking fun at stuff... hoping that he'd be able to help me laugh through the situation. Well, that's going to be a bit more difficult to do with the "subject of the joke"'s mother sitting right next to us.

So, what have I learned through all of this?
- I'm a lot more possessive of my fiancé than I thought I was.
- Though I don't have a jealous bone in my body, I am still human and humans (generally) don't like to see their mates mating with other humans... even if it's "pretend" mating.
- I really don't have a sense of humour!