Welcome to the forum! I hope you get a lot of feedback and support here! It certainly may not be necessary to unravel your primary relationship in order to pursue a poly lifestyle. Takes things slowly and deliberately.
My philosophy is that if the lifestyle can be beneficial to everyone involved then the chance of it being embraced increases.
First I had to explain the lifestyle to him and in a way that he can relate to. This took time. I could tell when he was staring to like the idea of it.
In my neck of the woods (also the conservative South) the lifestyle is easier for women, so I focus on supporting my partner and assisting him in his own efforts to create the type of poly life that he desires. As long as he is enjoying his poly life, he is supportive of my poly life.
There have been times when I basically put my poly life on hold for short periods of time in order to support and assist him in creating his.
This has worked well for us. I have suggested this approach to a few women that I know and when they started focusing on what type of poly identity and life their husbands wanted and remaining supportive of that- things improved for them as a couple.
Good luck and keep posting!
The key to life is in being fully engaged and peacefully detached simultaneously and authentically in each moment.