That indeed is a hard process. I sympathize with you both.
It sounds like you already have a good bit of experience in polyamory, and enough experience with monogamy to know that polyamory is the right thing for you. Now for the difficult part of working through this change with your husband.
If there's anything we can do to help, let us know. And, welcome to our forum.
Love means never having to say, "Put down that meat cleaver!"