Welcome to our forum.
I am sure things will be fine with you and your husband, you've been through a lot together, and he already knows polyamory is something you're interested in. Just be honest with him, and considerate of his feelings.
Maybe he's not ready to start polyamory yet, maybe he is and it will be a scary journey. But it is a part of your feelings and a part of moving forward in life, rather than living in a state of pretend, which could become stagnant.
I'm glad you could join us on Polyamory.com; I hope the various threads here will be of help to you.
Love means never having to say, "Put down that meat cleaver!"