Every one of them would be angry with you. You don't want to risk the displeasure of so many people. Certainly this alone should provide you with a high motivation for sharing. This will save you pain and embarrassment later when everything is in print and you can no longer change your mind. You will have eager responses to your request for feedback.
People simply love to express their feelings, ideas and reactions.
You can occupy many a fruitful hour listening to what they have to say about your plans. They will have many suggestions. You can record these and then consider them as you work on your outline. It is true that all these suggestions about your book are very likely to confuse you, but this entire process will aid you tremendously in your attempts to postpone the moment when you actually sit down and begin to write. Do not limit this sharing to your close relationships, even though you may have many friends with an abundance of ideas.