There is no one way to be non-monogamous, nor to be polyamorous. You and he will have so many opportunities to sort things out and come up with your own solutions that work for you. You and he and any possible future partners will create your own way of poly. Your opportunities to experiment, refine, adjust and learn will be endless.
There is no poly police who will arrest you or he for 'doing it wrong'. Now people may read here, if they have done something really dumb, that, hey, that was rather dumb. This is not the place for those sensitive to generally constructive criticism. (I'm not saying your husband is sensitive in this way, just making a general point.)
That said, your situation is not unique. Others have faced similiar situations, fears, and other emotions. In fact certain themes come up so frequently as folks struggle with poly that they become cliches, like the unicorn. There is no one way but others have come up with ways to handle conflict, to communicate more clearly, to figure out what is going on in one's own head that can be really useful to a newbie or someone who's been poly for decades. All we can do is say here is what worked for me in this situation. Use, adapt or ignore as you will.
Of course some people cannot learn unless they do it themselves. I tend to avoid people who can only learn this way because I often find them wearying. But that is just one of my many personal preferences. Obviously you will feel differently.