Hi Trollbear, welcome, I'm glad you've found us. We don't have all the answers, but many of us have been in one of your shoes.
I don't know if this is comforting or not, but you guys aren't an uncommon demographic with the already quite long relationship. There's definitely the possibility that this will end your marriage for good. Or there's the possibility that you will both transition to the new normal of polyamory. Often the biggest hurdle is overcoming the mono-normative cultural indoctrination that has permeated your life up until now, including the lauding of jealousy and violence (towards any other man that dares even glance at "your woman") as essential components of love and romance. If you can dismantle those ideas in your mind, it's actually rather liberating, and given this is polyamory.com, I for one, will be rooting for you to do the work to reach that new normal.
There's a heap of resources we can recommend when you're ready. But for the moment, just please know you're welcome here no matter where you are on your journey. You're welcome to post questions in poly relationships corner, or blog your journey in life stories and blogs.
The search function can yield a heap of stuff, but if you want to specifically discuss your own circumstances, feel free.
A poly "lifestyle" can actually mean a heap of different things, so often we call it a love style instead. (Swingers often say they are "in the lifestyle" and polyamorists are more likely to not be swingers but rather focus on the amory and relationship building side of things.)
Being polybombed can be a massive shock. But it doesn't have to be insurmountable. In fact, it's a sign that your wife absolutely does not want to end your relationship to go be with someone else. Your relationship isn't being usurped.
I hope she presented it to you as what's good for the goose is good for the gander!
All the best for your forthcoming discussions, and again, feel free to ask anything in this anonymous environment (nickname everyone you want to talk about).
kind regards
Evie